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| Blooming by Melina Meza |
Cortisol is a steroid hormone synthesized by the adrenal cortex and is released in response to stress and low blood glucose concentration. It is involved in numerous physiological activities, including regulation of blood sugar, metabolism of fat, protein, and carbohydrate, suppression of inflammation, activation of anti-stress pathways and influence on behavior and moods. The hormone’s response to stress includes:
- metabolizing glucose as an energy source
- mobilizing fat and proteins as a stand-by fuel
- triggering the immune response
- increasing the heartbeat, blood pressure, and mental alertness, all of which help in warding off the stress
After it is synthesized by the adrenals, cortisol is released into the blood stream where it gets bound to large proteins that facilitate its transport throughout the body. A small fraction of unbound free cortisol that is thought to be biologically active diffuses into cells and other bodily fluids. On a daily basis, a bit of cortisol is released in the early morning hours that help with the morning chores. The morning cortisol triggers the release of sugar into the blood stream and facilitates more blood to the brain and heart, all of which arouses us and puts us into action. In contrast, the level of cortisol gradually diminishes to its lowest levels around 10pm to coincide with the low physical activity in the night coupled with the sleep response. Salivary cortisol is perhaps the most reliable source for measuring the levels of cortisol. The concentration of cortisol in saliva accurately reflects the level of free cortisol in blood. Cortisol levels normally fluctuate throughout the day and night (diurnal variation), with a peak rise in levels at about 8 am and ebbing at around 4 am. To properly measure cortisol levels, saliva is collected four times in a day.
The adrenals secrete cortisol in response to a stressful situation, with the cortisol levels returning to normal following the stressful event. What is very important is that adrenals need time to recover after a stressful situation so they can do their job well if exposed to another stressful event. Unfortunately, in our present day high-stress environment, the body’s stress response is activated very frequently leaving very little recovery time for the adrenals. As a result, the adrenals are constantly under high alert and cortisol gets continuously released into the system. So cortisol levels remain high in the blood stream for greater periods of time, which can result in swelling of the adrenal gland itself, and an increased chance of all the negative effects as mentioned earlier (see Not So Sweet: Cortisol and the Problem with Sugar). The good news is that a regular yoga practice, including some restorative poses, guided meditations, and Savasana, regulates the cortisol levels so they are in balance, thereby keeping the adrenals healthy.
Further confirmation about the role of yoga in regulating the cortisol levels comes from a recent study on cancer patients Effect of Iyengar yoga practice on fatigue and diurnal salivary cortisol concentration in breast cancer survivors. Breast cancer survivors are at risk for chronic stress-related mental issues that alter the activity of the Hypothalamic-Pituitary-Adrenal axis, resulting in aberrant regulation of cortisol secretion, increased risk of immune dysfunction, and accelerated cancer progression. To study the effect of a yoga practice on cortisol secretion in breast cancer patients, researchers enrolled two groups of breast cancer survivors: one group that consisted of 9 individuals who attended a yoga practice for 90 minutes twice weekly for 8 weeks and a second group of 9 waitlisted individuals that served as a control group. The outcome measures included self-perceived psychosocial function and diurnal salivary cortisol secretion. The practice involved asanas in the Iyengar tradition that progressively increased in difficulty as participants gained strength and flexibility. The tests were conducted at baseline and after the 8-week study. Both groups completed a self report to document various aspects of psychosocial and physical functioning, and also collected salivary samples for cortisol analysis four times during the day for two consecutive days.
Not surprisingly, the yoga group had lower morning (8 am) and evening (5 pm) salivary cortisol and improved emotional wellbeing and fatigue scores compared to the control group, suggesting that a regular yoga practice may be a low risk, cost effective way to recover from physical and emotional stress, fatigue, and to regulate the levels of cortisol. The researchers postulate that yoga may impact the Hypothalamic-Pituitary-Adrenal (HPA) axis and the sympathetic nervous system (SNS) response to stress, possibly via direct vagal stimulation (see Vagal Tone and Yoga). In short, yoga may impact the endocrine and autonomic nervous systems together resulting in lowered cellular stress. Time to unroll the mat!
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