Tuesday, October 28, 2008

Insomnia, Breast Cancer, and Yoga

A study published in the Journal of Clinical Sleep Medicine has linked a disruption in heart rate regulation with insomnia in women with breast cancer. Insomnia symptoms were shown to be associated with a lower baseline of respiratory sinus arrhythmia (RSA), an important marker of the function of the parasympathetic nervous system. RSA is a naturally occurring variation in heart rate that occurs during a breathing cycle. The parasympathetic nervous system is a division of the autonomic nervous system, which acts as a control system that maintains a constant, stable condition in the body.

Lower RSA is associated with decreased parasympathetic functioning in insomniacs, which is in turn associated with increased stress and decreased emotional regulation. Diminished RSA has been associated with poor medical and psychiatric health.

Cortisol is a hormone often referred to as the “stress hormone” because it is involved in the response to stress. Cortisol levels normally peak early in the morning, while the lowest levels are present three to five hours after the onset of sleep. In one to two-thirds of women with metastatic breast cancer, cortisol levels are constant, go up and down throughout the day, or are elevated at the end of the day. Past research has linked insomnia to activation of the stress-response system, which results in an increased level of cortisol. Results of this study confirmed a relationship between frequent awakenings and abnormal cortisol rhythms in metastatic breast cancer. Lower RSA is associated with an increase in stress, which causes an increase in cortisol, which is linked to insomnia.

The activities of the autonomic nervous system are usually done without conscious control or sensation, but one, breathing, is done in connection with the conscious mind. One of the best ways to combat low RSA and regulate autonomic function is diaphragmatic breathing or breathing deeply into the lungs by flexing the diaphragm. Pranayama (translated as lengthening of the breath) breathing techniques learned through hatha yoga have been cited as treating stress related disorders and improving autonomic function.

Sleep disruption is two to three times more common in cancer patients than in the general population. These disturbances may exacerbate concurrent cancer and/or treatment related symptoms such as fatigue, mood disturbance, and gastrointestinal distress. They may also affect psychiatric illness and may lead to a reduction in quality of life and overall health, so it is especially important to treat insomnia in cancer patients.

- Science Daily Article summarized by Jasan Zimmerman

1 comment:

Siegfried said...

Hello, Friends - what a succinct summary, Jasan. I bet that similar findings (lowered RSAs) complicate healing other forms of life-threatening diseases. I have found, though, that diaphragmatic breathing has become counterintuitive for many women for aesthetic reasons. As a sleep-specialist, I have learned to advocate especially ex-halations because most people equate 'take a deep breath' with inhaling. (I Want to Sleep-Unlearning Insomnia) there is also another caveat: women who have been (sexually) abused experience deep exhalation as PTSD-triggers. It takes more than encouragement to make diaphragmatic breathing tolerable again. This might be important to keep in mind when you find a woman having trouble sustaining pranayama. As you might know, insinuating possible abuse has become an ethical/professional liability - still breathing will be compromised until the underlying traumatic 'anchors' have been addressed.