Relaxation is so much more fascinating and powerful than many people think. It doesn’t mean floating in a half-conscious state with your mind somewhere else. It means becoming more alive, more present, and more able to react to what is happening around you. It is a physical as well as mental state, and both of those elements – body and mind – need to be involved in order to achieve this presence, or what some people call mindfulness (or bodyfulness!).

This article is the first in a series of three, explaining how relaxation actually functions in your body-mind system, by looking at a physiological/neurobiological level, and using this understanding to explain how relaxation plays such a vital role in trauma therapy.

For this we will look at the physiology of the fear and stress responses, at a systematic level as well as at the muscle level. This physical level is the key to learning to rewire those fear/stress responses. I’ll explain which kind of effects can come from deregulated stress and fear responses, and I’ll give a tour through a few mind-body techniques that try to address these, which shows why mind-body techniques, bodywork and body psychology are so helpful for psychological as well as physical conditions.

Circadian Rhythms and Rest

Relaxation is a necessary part of being human. It’s not just for holidays, it’s not about being lazy, and it’s not something you have to earn. It is something you actually need for both your physical and psychological wellbeing. But what actually is it? I like words, so let’s look at what the word “relaxation” is accepted as meaning. The Oxford Dictionary defines relaxation as the state of being “free from tension or anxiety”, which it further splits into “recreation and rest”, and also the “loss of tension in a part of the body, especially in a muscle when it ceases to contract.” Let’s look at both of those levels – rest and muscle tension – in terms of the body’s systems.

Resting is part of our body’s daily rhythms, which are made up of an orchestra of hormones and neurotransmitters, regulating the activity of muscles, organs, glands and nerves, and the flows of enzymes, fuel, blood and lymph fluid. This orchestra is what gives us, among other things, more or less energy at different times of day.

One key player in this system is the hormone cortisol, which has a clear circadian rhythm. The level of cortisol is typically at its lowest during the night, rising sharply in the morning until around lunchtime and then gradually sinking down throughout the day. The basic function of cortisol is to raise blood sugar levels and increase alertness, giving us more energy. It also weakens the immune response.

A second key part of our circadian rhythm is the autonomic nervous system (ANS), which is responsible for controlling different aspects of organ function. The ANS is made up of two parts that act antagonistically: the sympathetic nervous system (SNS) is related to you being active, mobile, and coping with challenges; whereas the parasympathetic nervous system (PSNS) is related to you being in a resting state. An example of the circadian rhythm of the ANS is that PSNS activity is higher during deep sleep (NREM sleep), while the SNS activity is more present during dreaming (REM sleep).

If only rest were so simple...

From this we can see that on a physiological level, rest is not as simple as just lying down. It is a particular state of a complex system, which involves lower levels of cortisol and higher levels of parasympathetic activation. But the ups and downs of this system tend to get flattened out when the system’s rhythm gets disturbed; this ends with us having sleeping problems and general fatigue. In trying to understand how and why rest would get disturbed, we need to look more closely at these two systems in action.

Stress, Fear and Recovery

As well as their daily fluctuations, cortisol and the autonomic nervous systems are part of our ability to react to situations, especially stressful or fearful situations.

The SNS is not just about being more active; the sympathetic nervous system is the “fight or flight” response, which gets us ready to put all our energy into running away from or attacking something. This is controlled from the mid-brain, a deeper and older part of your brain than your conscious cortex. The SNS is active when we run or do exercise, and when we experience emotions ranging from joy and excitement to terror and rage.

SNS: heart rate up, blood pressure up, muscle tension up, heightened alertness, blood glucose up, digestive activity down, immune system down, insulin inhibited (preventing glucose storage)

It’s a similar story with cortisol. As well as varying during the day, cortisol is produced as a result of the “stress response”, or the hypothalamic-pituitary-adrenal axis (HPA axis). The HPA is triggered by fear, stress, physical activity and illness, as well as the sleep/wake cycle. It involves the hypothalamus in the mid-brain producing a hormone called CRF (corticotropin-releasing factor), which communicates with the pituitary gland, and ends with causing the adrenal glands to release the hormones cortisol and epinephrine. Like the SNS, this response happens in deeper parts of the brain than the thinking/conscious part, although there are also feedback loops with the cortex.

In situations when we are afraid, yet another system can kick in, called tonic immobility: a combination between freezing and collapsing. In evolutionary terms, this is older than the SNS, controlled from the brainstem, and can be seen in many animals. Evolutionarily, tonic immobility is a kind of shock state that comes into play if it seems like we won’t be able to successfully fight or flee, and that we’re going to be killed.


The stress response: hypothalamo-pituitary-adrenal (HPA) axis

We should note that although these fear systems were developed to deal with situations like being chased by bears, the same systems are activated in any situation in which we feel afraid and/or powerless, whether this is a threat to our physical or psychological safety.

After a stressful situation is over, when there is a perceived sense of safety, the parasympathetic nervous system (PSNS) should then gradually return us back to a balanced state, including reducing muscle tension, deeper breathing, and resetting hormone levels, enzyme secretions and all the rest of it. Cortisol should then gradually decrease. As animal research has shown, the parasympathetic rest and recovery after a fear situation also involves gentle trembling, shaking, deep breaths, sweating, and sometimes more aggressive fight-reenacting. In Somatic Experiencing, developed by Peter Levine, this process is known as “discharge”.

PSNS: heart rate down, blood pressure down, muscle tension down, digestive activity up, saliva secretion, immune system up, insulin released (allowing glucose storage)

As well as the daily rhythms, then, we can see that a physiological definition of rest includes being able to return to homeostasis after confronting a challenge to the system. This means being able to complete the stress/fear response and rest again afterwards. If the physiological system is able to reset after sympathetic activation, then we don’t develop the symptoms of trauma.

For various reasons, the parasympathetic discharge and return to normal afterwards often does not happen. In other words, we stay stuck in the stress or fear responses. Part of the reason for this can be linked to lifestyles of constantly being busy, stressed and on the go. Another reason is related to how we reacted to stressful, frightening our traumatic situations during our lives, and what effect this had on the resting state and reactivity of our stress/fear systems. We will look at these effects next, before turning to what is happening on the muscle level, which is one of the keys to learning to complete the fear response.

So far we’ve looked at how we could define rest in terms of body systems, and we’ve looked at what happens to those systems during the stress and fear responses. In the next article, which you can find here, we’ll come to how people stay stuck in those responses, and what kind of effects that can have in terms of both physical and psychological health.