Thursday, July 7, 2011
Sleep has always been a somewhat magical state with a mysterious purpose. In Hindu scripture, the world itself is considered the dream of a sleeping Vishnu.
Why do we need sleep? There is no good answer to this question, but it is an ancient biological process. Two stages of sleep, the Rapid Eye Movement (REM) stage, and the Delta-wave, or slow-wave sleep each have distinctive effects on different types of memory and decision making. Sleep is also a general healer. It promotes the rejuvenation of the immune, skeletal, muscular and nervous systems, and a healer of wounds.
Body Chemistry: There is a particularly strong effect of sleep on body chemistry. The important anabolic (body-building) hormones, growth hormone, and insulin are secreted preferentially during sleep and reduced by poor sleep. Reductions in sleep duration result in prediabetic chemistry-even a single disrupted night of sleep can alter insulin response in young, healthy people. Similarly, in one's youth, up to 70% of daily growth hormone is secreted during the deepest part of sleep. With ageing, this decreases with a fall in deep sleep. If we could increase deep sleep in the elderly, we might induce a younger hormonal pattern. Exercise and meditation both increase deep sleep.
How much is enough? The amount of sleep one gets seems to correlate with longevity; seven hours is the 'sweet spot'. A lack of sleep (5 hours or less) more than doubles the risk of cardiac death while too much (8 hours or more) seems to be associated with non-cardiac death. Too little sleep seems to be a particular risk factor for weight gain, hypertension and type 2 diabetes.
Naps: As India lurches towards a more Westernised life, the mid-afternoon nap may become rare. That would be a shame. A study from Greece confirms that regular napping (three times a week, 30 minutes) decreased the risk of coronary disease by 37%!
Factors that influence sleep: Caffeine In the West, caffeine is one of the major culprits in the sleep disruption of modern life- even more so in recent years. Tea has far less caffeine than coffee.
Exercise: Aerobic exercise that lasts for an hour will help you get to sleep and stay asleep. However, it may take up to three weeks for the full effect to be noticeable.
Alcohol: Alcohol at night reduces the healing benefits of sleep. While people fall asleep faster, alcohol increases lighter REM sleep and shortens slow-wave sleep and overall sleep time. As a result, it can cause more sleepiness the next day.
Melatonin: The body creates a chemical called melatonin, which may be a helpful sleeping aid in certain situations like jet lag, shift work, and general insomnia. I sometimes recommend it, particularly for post-surgical patients.
While some take melatonin nightly and tout it as an anti-ageing cure-all, I generally advise my patients to use it sparingly in specific settings until we know more about long-term effects. For jetlag, the optimal dose appears to be 5 mg, taken at bedtime in the new timezone; for insomnia, a dose less than one-tenth of that (0.3 mg).
The bottomline: Folk wisdom about the healing properties of sleep is absolutely correct. Too often it is neglected by physicians in their advice to patients. With a systematic approach and some discipline, you can improve your sleep, feel better and live healthier and longer!