Coming into Balance: How Stress and Relaxation Work Together

by Baxter and Nina

Mirror Image by Melina Meza

So, you’re lying on a beautiful beach somewhere, feeling the warmth of the sun on your skin and listening to the sound of waves lapping at the shore, and you’re feeling totally comfortable and very relaxed. So what is happening to you? Is this the relaxation response? The rest and digest state? Conscious relaxation? Or what?

Another time you’re sitting alone in your house, meditating on your breath. Your knee hurts a bit. Your thoughts seem wild, and you feel fidgety and restless. But you keep coming back to your breath, and after several minutes your mind begins to settle and quiet. What’s happening to you now? And how is this different than being on the beach?

Or, let’s say one night you’re driving your car down a dark, winding road through a forest when suddenly a deer bolts into the road. Your heart begins to pound and your breath speeds up as you quickly try to take evasive action. Is this the stress response? The Fight or Flight response? On another night, you’re meeting someone you’ve just started dating. When you spot them on the street coming toward you, your heart begins to pound and your breath speeds up. It feels kind of like stress, but in a good way—you know, exciting. What’s going on there?

As we have been delving into the topics of stress and relaxation, we’ve found there’s some confusing terminology out there in the literature and even here on our own blog! So it seems like a good idea to try and define once and for all some of terms that have been most commonly bantered about. To start, let’s take a look at the following terms to get clearer on what they mean:

1. Stress Response
2. Fight or Flight State
3. Relaxation Response
4. Rest and Digest State
5. Conscious Relaxation

Stress Response. This term describes the response of your mind and body response of your mind and body when you are faced with a challenge. Sometimes the response is to a real or perceived threat, ranging from serious life or death situations to stressful situations like doing your taxes or getting lost. Other times the response is to a positive challenge, such as running a race, falling in love, brainstorming ideas, or creating a work of art. The stress response increases the activity of your sympathetic nervous system, speeding up your heart and breath rates, and dilating your pupils to get you ready for action. When the stress response is at its extreme, you shift into the Flight or Fight State.

Fight or Flight State. This term describes the state of your nervous system when your sympathetic system is fully operational, and generally you actually are in danger, threatened, or think you are in danger. For example, if you are about to get into a car accident, your nervous system sends quick signals to your adrenal glands to release adrenalin, unleashing a rapid physical response evolved to get you to safety. (See below for details.) 

Relaxation Response. This term describes the response of your mind and body to safe circumstances or a secure environment, causing your heart and breath rate to slow, your blood pressure to drop, your energy usage to slow and your digestion and immune systems to turn on. In our above example, if you successfully avoided the car crash, once you got home and had some time to decompress, your system would slowly shift to the relaxation response. The relaxation response increases the activity of your parasympathetic nervous system, and enters you into the Rest and Digest state. 

You can trigger the relaxation response through conscious relaxation techniques or just by ordinary resting and relaxing while you are awake, such as by listening to calming music on your couch or by lying on a beach feeling the sun on your skin and listening to the waves. (This is in contrast to activities that are distracting rather than relaxing. For example, while TV distracts us from our real-life concerns, it is not actually relaxing your nervous system because the action you’re watching is typically very stimulating—as anyone who tries to go to bed after a scary movie or violent show soon realizes.)

Rest and Digest State. This term describes the state of your nervous system when your parasympathetic system is fully operational, you are mentally and physically relaxed, your body’s vital signs are in their calm state, and the immune, repair, and digestive systems are up and operating. You enter this state naturally when relaxing at home or out in nature, or when you use conscious relaxation to trigger the relaxation response.

Conscious Relaxation. This term describes any technique that triggers the relaxation response, including meditation, breath practices that are calming, guided relaxation practices, and even gentle and restorative yoga asana practiced mindfully. Keep in mind that this describes an active practice technique with a desired goal. But the awesome thing about conscious relaxation is that you can use it anytime and anywhere. You don’t need to fly to Hawaii. And although a quiet peaceful environment is helpful, you can even meditate or do breath practices in challenging environments. (See 6 Ways to Bust Stress with Yoga).

The Healthy Balance of Stress and Relaxation

So let’s say you’re sitting outside in the garden talking with a friend, and you’re feeling very comfortable and relaxed. Then your friend tells you about an interesting idea he has, and you suddenly perk up a bit. You then pitch in with an idea of your own, and that leads to very animated discussion. What’s happening here? Are you relaxed or stressed? Or, is it possible that you are both at the same?

Ding, ding, ding! Yes, it’s both at the same time. As we described in Chapter x, your autonomic nervous system, which controls background processes that keep your body alive and healthy, such breathing, maintaining normal temperature, and adjusting blood pressure to match activity, is divided into two subsystems: your sympathetic nervous system and your parasympathetic nervous system. And these two subsystems work together in tandem, providing you with a healthy balance of activity and relaxation. 

Sympathetic Nervous System. This system stimulates you when you need to be active. The activity can be as basic as getting out of bed in the morning, writing an email, or practicing gentle yoga poses, something more challenging such as running a race or giving a public talk, or something really drastic such as trying to avoid a car accident. 

Your sympathetic nervous system prepares your body and mind for action by stimulating your heart to beat faster and stronger and slightly raising your blood pressure to improve blood flow, by opening your airways so you can breathe more easily, and by stimulating your thought processes so you can assess your situation and think more quickly.

In extreme situations—where serious action on your part is needed—your sympathetic nervous system triggers the Fight or Flight response, as described above. In this state, your sympathetic nervous system actually turns off the background functions of nourishment, restoration, and healing that are provided by the parasympathetic nervous system because these functions will slow you down. Being in the Fight or Flight state is normal and healthy as long as it doesn’t happen too frequently or continue for a long period of time, when it becomes chronic stress (see see About Stress: Acute Versus Chronic).

Parasympathetic Nervous System. This system is responsible for nourishing, restoring, and healing your body and mind. As you move through your day, whether you are totally relaxed, slightly active, or even very active, your parasympathetic nervous system stimulates digestion, activates various metabolic processes, and keeps your immune system turned on. (These functions will only be turned off temporarily when you’re in a Fight or Flight state.)

When you are physically still and your mind is quiet, your parasympathetic system functions optimally, allowing you to enter the Rest and Digest state. Being in the Rest and Digest state is normal and very desirable, as it gives your body and mind time to relax completely and recover from stressful periods. There’s probably no downside to spending a lot of time in this state, except you probably wouldn’t get very much done!

On an average good day, when you’re feeling rested and cheerful, and are involved in normal work and social activities, your sympathetic and parasympathetic systems work together to keep you in balance, allowing you to be both fully functional and stay healthy. A well-balanced yoga practice, including both physical exercise and stress management practices, will help you maintain this balance when there are minor challenges in your life. It is only when you spend too much time with an overactive sympathetic nervous system due to ongoing stressful life circumstances that you can become out of balance. At this point, it’s very important to take steps to reduce your chronic stress and bring yourself back into balance again, as chronic stress is harmful to your physical, emotional, and mental health (see About Stress: Acute Versus Chronic). And conscious relaxation with yoga is the way!

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Your Nervous System Needs TLC

by Baxter and Nina

Nerve Cells

Although we tend to think about the nervous system only when we’re feeling stressed (or nervous!), your nervous system is essential for your survival. Basically, it provides the following essential functions:

• Controls background processes that keep your body alive and healthy, such breathing, maintaining normal temperature, and adjusting blood pressure to match activity.
• Responds to external stimuli (which come in through our senses), such as having a positive reaction to a beautiful smell, a pain response to a burn, or a quick reaction to an oncoming car 
• Obeys our conscious mental instructions, such as to talk, move, or breathe more slowly. 

By communicating through your nerves, your nervous system constantly monitors the internal activities of your body systems, attempting to keep them in a healthy balance called “homeostasis.” It also monitors your environment to assess if it is safe or dangerous, and sends messages to your body either to relax and enjoy or act quickly to get to safety. 

Your nervous system is made up of two main parts: the central nervous system and peripheral nervous system. However, even though we—and our anatomy books!—always discuss the central nervous system and peripheral nervous system as two separate systems (see below), they are really a continuation of one another and are in constant communication with each other about the state of your body. 

Chronic stress has a negative effect on your nervous system, contributing to the development of anxiety, depression, sleep problems, lack of concentration, and memory impairment. Therefore, using your yoga practice to keep stress levels in check and to manage your stress during challenging periods, will support the health of your nervous system overall. Additionally, besides by staying generally healthy through exercising regularly, eating a healthy diet and drinking enough water, getting enough rest, and avoiding smoking, you can support the health of your nervous system by:

• Treating conditions that can negatively impact the system, such as diabetes and hypertension.
• Avoiding alcohol and drugs that affect the nervous system. 
• Decreasing use of over-the-counter medications, because as you get older, these can negatively affect your nervous system. 
• Testing your hearing and vision regularly (when they are not working well the brain has a harder time recording information).
• Cultivating brain health (see 6 Ways to Foster Brain Health with Yoga). 

Now let’s have a look at the individual components so you can understand how they all work together, how important they are for your basic survival and functioning in your daily life, and how yoga can help you keep your nervous system healthy. 

Neurons. The basic component of your nervous system is a specialized cell called a neuron, which are both part of your brain and also make up your nerves. The human brain contains about 86 billion neurons, and its neurons are densely packed and are only 10 microns long. While aging results in the loss of some of our brain neurons, the ability of our brains to grow and change (brain plasticity) means that continuing to stimulate our brains with learning will actually cause our brain neurons to grow and existing brain neurons to be repurposed. 

Neurons connect the brain proper to your spinal cord, and from the spinal cord connect to neurons in your peripheral nerves. Using your asana practice to maintain healthy posture and proper alignment of your spinal bones will help to keep your spinal cord safe from pinching and narrowing, which could cause nerve dysfunction or pain. 

Your peripheral nerves consist of longer neurons, which can be up to 1 meter in length. They transmit messages through the nerve via electrical signals and use chemical neurotransmitters to send the impulses from one neuron to the next. A sedentary lifestyle and structural injuries can negatively impact your peripheral nerves. With a regular asana practice, you can release holding patterns around your nerves, allowing them to function them better. 

Central Nervous System. Made up of your spinal cord and your brain, your central nervous system receives and processes information from all over your body. In response to conscious thoughts, your central nervous system sends nerve impulses to your peripheral nervous system to make the requested action happen. And in response to nerve impulses that your central nervous system receives from your senses and your autonomic nervous system (which keep your background systems in balance), your central nervous system sends nerve impulses to make your body react appropriately. 

Besides communicating through your nerves, your central nervous system also communicates with your organs and the rest of your body through chemical and hormonal messages, for example, by releasing the stress hormone adrenaline when you need to react quickly. 

Peripheral Nervous System. Consists of nerve fibers that branch off from your spinal cord and extend to all parts of your body, including your neck, arms, torso, and legs, as well as all your muscles and internal organs. The nerve receptors and long nerves that travel all over your body and back to your central nervous system are either delivering information to your central nervous system or receiving instructions from it. For example, when you decide to raise your arms in Warrior 1 pose, your brain sends a message via the peripheral nervous system to the appropriate muscles. Or, when you’re stressed, your peripheral nervous system speeds up your heart rate. Likewise, if you cut yourself, taste some chocolate, or sniff a flower, your peripheral nervous system communicates lets your brain know all about it. 

The peripheral nervous system is divided into somatic and autonomic systems.

Somatic Nervous System. Provides voluntary control of your body movements. In yoga, we use our somatic nervous system when we practice poses, perform breath practices, stay still when we meditate, and consciously relax muscles in restorative poses and guided relaxation. Obviously we want our somatic nervous to function optimally because to function well in our daily lives we need quick and coordinated responses to our mental requests for movement or rest. You can use your asana practice to support the health of your somatic nervous system by practicing a wide variety of poses and movement patterns to activate all those nerves on a regular basis, and by practicing balance and flow poses to keep your proprioceptors (the nerves that allow you to sense where you are in space) healthy. 

Autonomic Nervous System. Regulates involuntary body functions, such as heartbeat, blood flow, breathing, and digestion. It’s called “autonomic” because it works autonomously (automatically) without your conscious effort. (You don’t need to tell your heart to beat the same way you need to tell your front knee to bend to 90 degrees in Warrior 2 pose. Voluntary movements, such as knee bending, are controlled by your somatic nervous system.) 

Although the functions of the autonomic nervous system are generally involuntary, some of them are not outside of your awareness, and they may be influenced by your state of mind. For example, although you can’t tell your heart to beat faster or more slowly, you can feel it beating. And when you’re calm, you’ll notice that your heart beats more slowly and when you’re afraid or angry, you’ll notice it beating more rapidly. 

The autonomic nervous system is divided into two parts that function in tandem with each other: the sympathetic nervous system and the parasympathetic nervous system. Learning about these two systems and how they interact with each other is one of the secrets to learning to keep your stress levels in check (see Life Changer: Understanding Your Nervous System). 

We hope this little anatomy lesson helps you understand the importance of your nervous system and the value of giving it active attention as you age. All the yoga tools at your disposal, including asanas, meditation, breath practices, relaxation practices, and even yoga philosophy, will help you support its good health.

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Pranayama: A Powerful Key to Your Nervous System

by Nina

Cliffs of Varengeville, Gust of Wind by Claude Monet

One of the methods we recommend that you can use to switch your nervous system from Stress mode (Fight or Flight) to Relaxation mode is by practicing breath awareness (see  The Relaxation Response and Yoga). Simple breath awareness provides a focus for your mind that allows you to trigger the Relaxation Response in the same way that meditating on a visual image, a mantra, or any other physical sensation does.

But what about pranayama, the formal practice of breath control? Although practicing pranayama takes quite a bit of focus and is a good way to take your mind off regrets about the past, worries about the future, or negative reactions to the present, it turns out that the reason pranayama works is quite different than simple breath awareness.

Understanding how pranayama works will help you appreciate why it is so powerful. And it will also help you chose the most appropriate practices for your particular condition. This is because—and many people don’t realize this—not all pranayama practices are relaxing. Some are quite stimulating in fact, and others should be considered more “balancing” than quieting. Let’s look at why that is.

Your autonomic nervous system is the part of your nervous system that controls the functions of your body, such as digestion, heartbeat, blood pressure, and breathing, that are “involuntary,” meaning the functions that you don’t have to think about (see Anatomy Lesson post). The autonomic nervous system is also the part of your nervous system that sends you into Stress mode (Fight or Flight) and that triggers the Relaxation Response (Rest and Digest). And while you cannot tell your nervous system directly to slow your heart beat, digest your food more quickly (that would be nice, wouldn’t it?), or to start relaxing right this minute, you can control your breath.

Think about it: even though you breathe without thinking about it, you can intentionally hold your breath, speed up your breath, slow down your breath, breathe through one nostril instead of the other, and so on. And this ability to alter your breathing is what gives you the key to your nervous system, providing you with some control over its “involuntary” functions.

This happens because of the relationship between your heart and lungs and the nerves between them. For each round of breath you take, during your inhalation, the nerves stimulate your heart to beat a little faster and then, during the exhalation that follows, your nerves stimulate your heart to slow down a bit. The overall effect is very little change in your heart rate from minute to minute. But when you make one part of your breath cycle, either the inhale or the exhale, longer than the other, and you do this for several minutes, the accumulated effect is that you will either slow your heart rate down (with a longer exhalation) or speed it up (with a longer inhalation) from where you started.

Stimulating Practices. When you make your inhalations longer than your exhalations, for example, by using a two-second inhalation and a one-second exhalation (2:1 ratio), and you maintain that for several minutes, your heart rate will speed up a bit. This increased heart rate sends a feedback message to your brain that your circumstances require activity, stimulating the Sympathetic portion of your Autonomic Nervous System to prepare you physically and mentally to take action with the Fight or Flight or Stress response.

So pranayama practices that lengthen your inhalation are practices you might want to do if you need energizing or are feeling depressed or lethargic. You would want to avoid them if you are feeling hyper, stressed out, anxious, or are suffering from insomnia. 

Calming Practices. When you make your exhalations longer than your inhalations, for example, by using a one-second inhalation and a two-second exhalation (1:2 ratio), humming on your exhalation with a Bhramari breath, or using your tongue tongue to slow your exhalation with a Sitali breath (see Managing Hot Flashes) and you maintain that for several minutes, your rate slows down a bit. This decreased heart rate sends a feedback a message to your brain that your circumstances are more peaceful and calm now, which stimulates the Parasympathetic portion of your Autonomic Nervous to allow you to rest, recover, and heal with the Rest and Digest or Relaxation Response.

So pranayama practices that lengthen your exhalation are practices you might want to do if you need hyper, stressed out, anxious or suffering from insomnia (they are excellent for doing in bed in the middle of the night). Since typically most of us aren’t really “under-stressed,” about the only time I can think you’d want to avoid these practices are if you are falling asleep and don’t want to.

Balancing Practices. When you make your inhalations and your exhalations the same length, for example, by using a two-second inhalation with a two-second exhalation or by practicing Alternate Nostril Breathing, you are only very subtly affecting your nervous system, maybe only slightly stimulating or calming it (depending on your current state). So these practices are good for times when you feel like you need “balancing” more than calming or stimulating or for when you wish to do a formal breath practice that will harness your mind in the present moment without having a strong effect on your nervous system.

Caution: For completeness, I’m listing forms of pranayama in this post that in the Iyengar tradition are not recommended for beginners. This is because they can indeed have a very powerful effect on your nervous system. Generally, 1:2, 2:1, and Brahmari breath are considered safe practices (although you should never let yourself get short of breath), but I do recommend that if you are interested in experimenting with pranayama that you study with a trained teacher.

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About Stress: Acute Versus Chronic

by Nina

We go on and on about stress management on this blog, don’t we? Well, that’s because the more we learn about the effects of chronic stress on the body, mind, and emotions, and the relationship between chronic stress and various diseases of aging, such as heart disease and hypertension, the more convinced we are that practicing yoga for stress management is one of the most important things you can do to promote healthy aging in the long term and enhance the quality of your life in the short term. 

But even though we think managing stress levels is so critical, it’s important to understand that stress in and of itself is not a bad thing. In fact, in certain situations, it’s actually a good thing. So today I’m going to do a little compare and contrast between acute and chronic stress and discuss how your nervous system responds to both. Yes, it’s another one of my little anatomy lessons but it is one that can have a profound effect on your physical, mental, and emotional health.

About Acute Stress

It was 5:04 on October 17, 1989 when the Loma Prieta earthquake hit. I was about to leave my Berkeley house to go grocery shopping with my five year old daughter at my side and my baby in his stroller when I felt such a violent shaking that I knew the quake was going to be a big one. I quickly looked around the house to find the safest place for us to be, and then grabbed my daughter and moved the three of us under a reinforced doorway. It turned out that our lives weren’t really in danger—though the framed artwork over the fireplace did come crashing down—but it was good to know that in an emergency, I could think and move with speed and clarity even while the floor underneath me was rolling and shaking. Although I didn’t realize it at the time—I was too busy reacting in the moment—my nervous system had switched into Stress mode (aka Fight or Flight mode, which is sometimes called Tend and Befriend for women). 

This is a dramatic example of a time in my life where I experienced acute stress. In my post Life-Changer: Understanding Your Autonomic Nervous System, I described how your nervous system responds to perceived danger or extreme physical activity. Preparing you to fight, run, or take evasive action, your autonomic nervous system releases hormones—adrenaline and noradrenaline—to increase your heart rate, blood pressure, blood flow to the muscles, and widens (dilates) your airways to make breathing easier. It also causes your body to release stored energy and increases muscle strength. And to increase your ability to assess your current situation and make important decisions, your nervous system causes your mind to race. So during that earthquake, my nervous system was doing just what it needed to do!

After the quaking stopped, we went outside onto the street to see what happened to the neighborhood. When we realized that everyone and their homes were all fine, we started to calm down. There was still some stress and worry while we waited to hear that my husband was safe and for him then to get home (which took several hours). My baby, of course, had no clue what was going on and I put him down at the usual time, but my daughter had to see her father before she could even think of going to sleep so I had her stay up with me (of course, even children feel stress).

By the next day, safe and reunited, we were feeling pretty normal as we dealt with the aftermath, like taking the brick chimney down (it had shaken dangerously loose). Of course, we were sad and horrified at the loss of life and property that occurred as a result of the quake, especially in nearby Oakland, where the double decker freeway collapsed. But our nervous systems recovered pretty quickly. 

After a bout of acute stress, you settle back down to normal. Your nervous system reduces the levels of stress hormones in your body, slowing your heart rate, decreasing blood pressure, reducing oxygen intake, and so on—your organs don’t need to work as hard now that the stressful situation has passed. And, now that you’re out of danger, your racing mind will also slow down. Your nervous system also stimulates your digestive tract to process food, eliminate waste, and use the energy from the processed food to restore and build tissues. After all, you need to build yourself back up after being depleted by a period of stress. 

Acute stress is a short-lived episode that is a natural, healthy response to danger, a perceived threat, or a physical challenge. And this is something we cannot and should not eliminate from our lives because even if we’re not living not in an earthquake zone, we all need to get out of danger sometimes, whether that means getting out of the way of an oncoming car or protecting a family member from a threat. But our stress response also prepares us for some really good things in life, including running a race, traveling to a foreign country, having a creative brainstorm, falling in love with someone, and even having an orgasm. 

About Chronic Stress

Back in the early nineties when my husband and I were raising our two children, I had a job as the documentation manager and lead technical writer at a software start-up company. As you might imagine, the pressure was intense as our small company struggled to meet our first deadline, the first test of the product by real customers (who needed my manuals to teach them how to use the product!) and balancing my work/home life was a definite challenge. As the deadline approached, I started working overtime. And I began having terrible insomnia—I could fall asleep but would be wide awake after just a couple of hours. I also started losing weight because the stress made me so feel nauseated that I lost my appetite.

Even though I wasn’t in the middle of an emergency, my nervous system was doing the same thing it had been doing during the earthquake, keeping my body and mind ready for fight or flight, but it was now a problem because the stress never let up and I had no chance to rest and recuperate. Eventually I was so anxious, exhausted and nauseated that even though I met my deadline (and the company went on to success), I couldn’t bounce back to normal health and my stress-related problems continued to plague me. It took a year and half of therapy, medication, and lifestyle changes to recover completely. (This was before I had the knowledge I do now both of the nervous system and how yoga can help.)

Unlike acute stress, which is short-lived and in response to a single event, chronic stress is ongoing stress that never lets up. Many different life circumstances can cause chronic stress, from job pressures, marriage or family problems, and financial or health problems to living in a stressful environment, such as a dangerous neighborhood or war zone. But regardless of the reasons, when your nervous system is continuously on the alert, and your body and mind never have a chance to recover and recuperate, your body and mind become overtaxed. And some of the serious health problems that can be caused by chronic stress include:

• heart disease 
• hypertension (high blood pressure) 
• insomnia and/or fatigue 
• digestive disorders 
• headaches 
• chronic anxiety or depression 
• weakened immune system 

But helping you manage chronic stress is where yoga really shines. Sometimes you can change your circumstances and your yoga practice can help support you through those changes, but other times circumstances are out of your control. Either way, yogic stress management practices (see The Relaxation Response and Yoga) and yoga philosophy (see Why You Should Study Yoga Philosophy) can help you face difficult challenges while at the same dialing down your stress levels. Maybe you will even be able to move toward equanimity. After all, the Bhagavad Gita defines a yogi as: 

“Who unperturbed by changing conditions sits apart and watches and says “the powers of nature go round”, and remains firm and shakes not. —trans. by Juan Mascaro

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Life-Changer: Understanding Your Autonomic Nervous System

by Nina

An Examination at the Faculty of Medicine, Paris by Toulouse-Lautrec

We’re going to have an anatomy lesson today! I know, I know, you thought after you graduated, you wouldn’t need to be learning any more dry, technical stuff. But I swear to you this information is so useful that it could literally change your life (see 2 Steps to Take Charge of Your Stress or Anxiety). I know that because it has changed mine.

So, take a deep breath and take a look at the autonomic nervous system. Your autonomic nervous system is the part of your nervous system that regulates involuntary body functions, such as heartbeat, blood flow, breathing, and digestion. It’s called “autonomic” (hahaha, I just learned this) because the system works autonomously (automatically) without your conscious effort. (You don’t need to tell your heart to beat the same way you need to tell your front knee to bend to 90 degrees in Warrior 2 pose. Voluntary movements, such as knee bending, are controlled by your somatic nervous system.)

Although the functions of the autonomic nervous system are generally outside of voluntary control, they are not outside of your awareness, and they may be influenced by your state of mind. For example, although you can’t tell your heart to beat faster or more slowly, you can feel it beating. And when you’re calm, you’ll notice that your heart beats more slowly and when you’re afraid or angry, you’ll notice it beating more rapidly. 

The autonomic nervous system is divided into two parts that function in tandem with each other: the Sympathetic Nervous System and the Parasympathetic Nervous system. After the autonomic nervous system receives information about your body and the external environment, it responds by stimulating body processes, usually through the sympathetic division, or inhibiting them, usually through the parasympathetic division. (Some sources also include the gut nervous system, or the Enteric Nervous System, as a third, separate part of the ANS. But I’m not going to take a stand on that anatomical debate.)

About Your Sympathetic Nervous System

Your Sympathetic Nervous System (SNS) prepares your body for stressful or emergency situations. That’s why it is commonly called the Fight or Flight response. To prepare your body to deal with a challenging situation or an emergency, your SNS releases hormones—adrenaline and noradrenaline—to increase your heart rate, blood pressure, blood flow to the muscles, and widens (dilates) your airways to make breathing easier. It also causes your body to release stored energy and increases muscle strength is increased. After all, you might need to fight or run! Something that is mentioned less often, but that I’ve really noticed myself and which is really pertinent to yoga, is that your SNS causes your mind to race to increase your ability to assess your current situation and make important decisions. 

Importantly, while your SNS is stimulating certain processes, it is also slowing body processes that are not needed in emergencies, such as digestion and urination. Healing, including restoration and building of tissues, is also slowed down. So you can see why you don’t want to be in a state of stress 24/7! 

In addition, because your body is working extra hard during stressful periods, it can just wear you out faster, which is why heart disease is associated with stress. And having a racing mind all the time, well, that causes emotional problems, such as anxiety and depression, as well as insomnia because you can’t let go and just fall asleep. All this why chronic stress is so harmful to your physical as well as emotional health (see Chronic Stress: An Introduction and Stress, Your Health, and Yoga for more info about chronic stress.) 

We can’t and should not eliminate stress entirely from our lives. Sometimes in the modern world we do need to get out of danger, including mundane situations such as getting out of the way of an oncoming car, or more in more rare circumstances, such as protecting a family member from a threat. But our stress response also prepares us for some really good things in life, including running a race, traveling to a foreign country, having a creative brainstorm, falling in love with someone (that can be so scary, right?) or even —ahem—having an orgasm. 

But problems arise when we’re living in a state of chronic stress due to demands of ongoing challenges, such as our job, commuting, or family problems. In this case, understanding what the symptoms of stress are can help you identify your current state. Because when you realize you’re stressed out, you can and should try to reduce your stress levels. And the thing that most people don’t realize is that you can intentionally change your nervous system from being in the stress mode triggered by your SNS to a different state.

About Your Parasympathetic Nervous System

Your Parasympathetic Nervous System (PNS) controls your controls body process during ordinary situations, enabling you to recover from stressful periods. That’s why it is sometimes called the Rest and Digest response. The PNS reduces the levels of stress hormones in your body, slowing your heart rate, decreasing blood pressure, and so on. After all, these organs don’t need to work as hard now that the stressful situation has passed. And, now that you’re out of danger, your racing mind will also slow down and you’ll experience feelings of relaxation (the PNS is also sometimes called the Relaxation Response). 

Importantly, the PNS stimulates your digestive tract to process food and eliminate wastes, and using the energy from the processed food is to restore and build tissues. After all, you need to build yourself back up after being depleted by a period of stress. So you can see how vital it is to spend some time in this mode, in which you are resting, recovering, and acquiring energy. 

It’s important to understand that Rest and Digest state is quite different than sleep (see Conscious Relaxation vs. Sleep). That’s why sleeping—if you can sleep—doesn’t fix stress-related problems, such as heart disease, high blood pressure, headaches, digestive problems, and so on. And, as you may have noticed, sleep also doesn’t quiet your mind, either, as many stressed people spend their days feeling anxious or wake in the middle of the night with a racing mind. That has a profound effect on your emotional well-being. So the bottom line is that if you want to do your best to protect both your physical and emotional health, you need to make an effort to less time in stress mode and more time in conscious relaxation mode. 

But, if your autonomic nervous system is “automatic,” how exactly can you change it?

Influencing Your Autonomic Nervous System with Yoga

Remember, I said earlier that although the functions of your autonomic nervous system are generally outside of voluntary control, they may be influenced by your state of mind. I also said that the autonomic nervous system responds to information that it receives from both your body and the external environment. And this is why yoga is such a powerful solution for managing stress. 

Quieting Your Mind. Yes, it turns out the original purpose of yoga described in the Yoga Sutras as “the stilling of the changing states of the mind” is one of the keys. By meditating—which typically involves concentrating on a non-stressful sight, sound, or physical sensation—you can quiet your mind. This in turn switches your nervous system from stress mode to relaxation mode. (See The Relaxation Response by Dr. Herbert Bensen for complete information on this.) 

Working with Your Breath. It also turns out that pranayama—or breath control—allows you access your nervous system. By slowing your breath, as it would be in a state of relaxation, you can actually switch your nervous system from stress mode to relaxation mode. Baxter described how this works in his post How Your Breath Affects Your Nervous System.

Working with Your Environment. Finally, you can use your asana practice to create physical environment that will encourage your nervous system switch from stress mode to relaxation mode. Practicing relaxing or quieting yoga poses, such as restorative poses and supported forward bends, in a warm room, will send messages to your nervous system that you’re safe and comfortable. Yoga nidra and other forms of guided relaxation that you practice in Savasana will have the same effect. Inverted poses are a special case because these yoga poses take advantage of the mechanisms in your body that control your blood pressure to “trick” your nervous system into switching into relaxation mode (see Why You Should Love Your Baroreceptors). 

See The Relaxation Response and Yoga for more information about how you can use yoga to trigger the relaxation response. 

Well, it seems I’ve gone on much longer than I expected, but I felt I had some important things to explain. For those of you who didn’t already know this information about the nervous system, I hope you will find it as compelling as I do, and that it will empower you to deal more effectively with stressful situations and reduce your overall stress levels.

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The Negative Effects of Inactivity on Your Nervous System

by Ram

Office at Night by Edward Hopper *

In the Yoga Sutras, Patanjali describes styana (inactivity, sedentary) as one of the several distractions that serve as obstacles on the journey toward perfect health and enlightenment. Data gathered from 33 countries indicate that sedentary lifestyle accounts for six percent of all cases of coronary heart disease, about 7 percent of type 2 diabetes, and 10 percent of breast and colon cancers. That puts inactivity up there with smoking as a possible barrier to increasing life expectancy (see Inactivity 'killing as many as smoking'). 

A sedentary lifestyle is one in which, among other things, you sit for more than 3 hours, sleep for extended periods of time, watch long hours of TV, or simply idle away the time. But humans are designed for movement and physical inactivity is against the evolutionary norms for humans as the human body simply is not built to be inactive. Go back to history and notice that pre-historic men were always active—often quite strenuously—to get food, find shelter and simply survive. They naturally spent a lot of time outdoors walking, hunting, gathering, and performing various other physically oriented tasks. To them this was not a physical exercise or "working out"; it was just normal life.  In today’s world, however, activity/exercise is primarily an intervention—something we do to guard against the negative impacts of a sedentary lifestyle.

Inactivity is not only having an impact on public health but also seems to decrease the life span of the individual. Studies reported in prestigious medical journals suggest that prolonged inactivity is the cause of one in 10 deaths worldwide. Adults in the U.S. spend an average of 55 percent of their day engaged in some kind of sedentary behavior (see Sedentary behaviour and life expectancy in the USA: a cause-deleted life table analysis). Such prolonged inactivity puts an individual at risk for many chronic diseases, particularly cardiovascular disease, Type 2 diabetes, obesity, and high blood cholesterol. It also weakens the musculoskeletal system, increasing the likelihood of osteoporosis and the risk of falls and fractures. Those who maintain a reasonable amount of activity particularly across the middle and later years are twice as likely to avoid early death and serious illness compared to the inactive individuals. 

This reminds me of my earlier post The Power of Mental Exercise, Part 1 where I mentioned that our brain is "plastic," which refers to the brain's capacity to rewire itself through mental activity, learning and experience. When we learn new things, our brains put out new neural branches and form new connections; the brain constantly changes and rewires in response to experience and learning. Plasticity is the reason why stroke patients can relearn skills after sustaining brain damage. Plasticity also explains how a healthy part of the brain might assume the job of a damaged part. Studies have shown that physical and mental exercise rewires and remodels the brain. 

Having realized the ill effects of inactivity on the physical body, researchers took the next and the most obvious step of investigating the effects of inactivity on the brain and cognition. Very little is known about whether inactivity alters the structure of the brain and the subsequent consequences that arise as a result of this alteration. But common sense and our own personal experiences tell us that we feel depressed, dull, or gloomy after prolonged inactivity. Some of us even complain of “fogginess” or “murkiness” after idling away for prolonged periods. 

In order to obtain empirical data on the relation between inactivity and brain health, researchers performed experiments on mice. Scientists gathered two groups of rats and placed one half of them in cages with running wheels to keep the rodents very active. The other group was kept in cages that restricted their total activity so this group would remain sedentary. After three months, the animals were injected with a special dye that colors a specific set of neurons in the rostral ventrolateral medulla, a region of the brain that controls the autonomic nervous system (ANS) activities, including breathing, blood pressure, and other metabolic functions central to our existence. An advantage of monitoring this specific area in mice is that in humans this region of the brain functions similarly. When the ANS functions optimally, information from the neurons travels to the heart in a coordinated and regulated manner. This causes the blood vessels to either widen or contract as demanded by the situation. A disorderly and overly active ANS is problematic as it could turn on the sympathetic part of the system erroneously, which could result in faster heart and breathing rates, and increases in blood pressure. 

When the scientists dissected the brains of rats in the above-mentioned study, they found noticeable structural and functional differences between these two groups. Inactivity not only affected the neurons and brain function but the heart as well. While the neurons in the brains of the active rats were well shaped, had perfect branching, and were functioning normally, inactivity triggered unregulated and unrestricted neuronal branching making them hyper sensitive. This in turn resulted in erratic hyper-activation of the ANS and cardiovascular disease. In effect, these neurons had changed in ways that made them likely to over-stimulate the sympathetic nervous system, potentially increasing blood pressure and contributing to the development of heart disease. The findings are important as they address the mechanism by which inactivity increases the risk of heart disease. Though the study was primarily done in mice, the risks associated with inactivity can be extrapolated to humans as well.

By encouraging you to be physically and mentally active— helpful for preventing a whole host of health problems—we’re doing you a favor. Instead of idling away your time or sitting on the couch watching a TV show, there is no reason you can’t simply get off the couch and do a little bit of yoga, right next to the couch (or anywhere else in your house). This blog has got lots of mini practices that you can do. You could try a practice you find in a yoga book or DVD, or you could just start out with a Reclined Leg Stretch or a Downward-Facing Dog pose and see what happens next.  If you skip just one TV program, you can do a half an hour of yoga without even leaving the house (see Creating a Mini Yoga Practice). On our blog, we’ve got yoga poses you can do at work, at the airport, or anywhere else you can’t roll out a yoga mat. Whatever it is that you do, make sure you are more active and just have fun incorporating a home or office practice. You’ll be surprised at how rewarding it is!

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Falling for Yoga Myths: Yawning and Sighing and the Nervous System

by Nina

Heart and Lungs

I hope you realize by now that there are a lot of myths out there in the yoga world, such as that yoga nidra is an ancient practice or that Sun Salutations have been practiced for thousands of years. So here at Yoga for Healthy Aging, we try to do a bit of fact checking before we go ahead and write about a subject, whether it is medical, scientific, or historical. And when I edit a post, I try to confirm anything that looks a bit, well, suspect. But once in a while, I’m less than meticulous, and that can result in an error or two. After I read what Baxter wrote about the relationship between the breath and the nervous system in his post How Your Breath Affects Your Nervous System, I asked him to take a look at a related post I wrote some time ago called Your Key to Your Nervous System: Your Breath because I was concerned that perhaps my original post had errors in it. Although at the time I had been writing about what I was convinced were facts, Baxter confirmed that some of the information in my post about yawning and the affect of the breath on the nervous system, which I had learned from a yoga teacher, was actually incorrect. Baxter identified this misinformation as a yoga myth—ideas that seems to get perpetuated, despite the fact there is no proof of their validity.

So this post today is an update to my original post, with Baxter’s comments/corrections on my original statements. Well, it’s a journey for us, too, right?

YOGA MYTH: Nina wrote, “Have you ever wondered why you tend to yawn when you’re sleepy? Well, a yawn is a great big inhalation. And because your heart rate tends to speed up on your inhalation, that yawn in the middle of that boring lecture or business meeting is little message to your nervous system: wake up! On the other hand, when you are upset about something, you tend to sigh. That sigh—try one!—is an extra long exhalation. Because your heart rate tends to slow on your exhalation, that sigh while you are feeling emotional turmoil or are just stuck in traffic is a little message to your nervous system: take it easy, buddy, slow down a bit.”

BAXTER’S CORRECTION: Here’s what I found…and it does not seem to confirm your suggestions that it is the heart rate effects that are driving the yawn or sigh. There are four theories about why we yawn, none proven or much studied:

• Physiologic theory: Our bodies induce yawning to draw in more oxygen or remove a buildup of carbon dioxide. At least one studied seems to have disproved this theory.
• Evolutionary theory: Some think that yawning began with our ancestors, who used yawning to show their teeth and intimidate others. An offshoot of this theory is the idea that yawning developed from early man as a signal for us to change activities.
• Boredom theory: Although we do tend to yawn when bored or tired, this theory doesn't explain why Olympic athletes yawn right before they compete in their event or why dogs tend to yawn just before they attack. It's doubtful either is bored.
• Brain-Cooling theory: a more recent proposal is that since people yawn more in situations where their brains are likely to be warmer—tested by having some subjects breathe through their noses or press hot or cold packs to their foreheads—it's a way to cool down their brains. Cool brains think more clearly.

Why do we sigh? As it turns out, sighs do seem to work like the brain’s reboot button for regular breathing. According to a 2010 study Take a deep breath: The relief effect of spontaneous and instructed sighs, during mental stress, the volunteers’ breathing became more and more irregular as participants increasingly relied on deliberate breath control, at which point, a sigh occurred, causing automatic regular respiration to kick in again. Furthermore, muscle tension steadily built up before a spontaneous sigh and decreased afterward, supporting the idea that sighing helps release tension.

YOGA MYTH: Nina wrote, “It turns out that by intentionally taking in more oxygen (either by speeding up your breath or by lengthening your inhalation) you can stimulate your nervous system and that by taking in less oxygen (by slowing your breath or lengthening your exhalation), you can calm yourself down. It’s that simple.

BAXTER’S CORRECTION: It is actually likely not that simple, as the effect I described in my post How Your Breath Affects Your Nervous System really more clearly explains what happens: the inhale speeds up the heart rate (not because of O2 levels) and the exhale slows it down (not due to O2 levels, but due to the nerve input from breath cycle to heart). As the heart rate slows more over the course of five minutes of 1:2 ratio breathing, for instance, the slower heart rate is monitored by the brain and leads to even further turning on of the parasympathetic Rest and Digest response. And, in fact, carbon dioxide levels in the blood stream have a much greater influence on the rate of breathing than O2 levels, and are monitored much more closely by the brain moment by moment and lead to adjustments in the ANS tone of whether sympathetic or parasympathetic nerves are stimulated. The importance of “getting more oxygen” in is a myth that has been propagated for a long time by yoga teachers in this country. For further information, see Leslie Kaminoff’s article What Yoga Therapists Should Know About the Anatomy of Breathing.

CONCLUSION: Well, we're all learning this stuff together. Even Baxter went ahead and did a bunch of new research. And, sigh, at least I was right about sighing.

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