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The importance of sleep



For LiveWell
Tuesday, June 28, 2016

The three fundamental needs for human survival are nutrition/food, physical activity and sleep. We can go without activity for months, without food for days to weeks, but we can only go without sleep for hours to days before we are severely impacted. Animal studies show that if deprived of sleep for 2 to 3 weeks, the animal will die. We sleep for about a third of our life, so it is clearly essential.

Truth be told, we still do not fully understand sleep. We know that it is an unconscious state that occurs on a daily basis from which we spontaneously recover. As we go to sleep, the electrical activity of the brain decreases which is seen as a slowing of brainwaves. There are four separate stages of sleep which are characterized by brainwave speed and size. The stages are Stage 1,2,3, and dream sleep (REM). The deeper our sleep, the slower and larger the brainwaves become. The deepest sleep is called slow wavesleep or Stage 3 sleep. All sleep is important, but Stage 3 and REM sleep appear to be the most important. When individuals are sleep deprived and then later allowed to sleep, there is a pronounced rebound in Stage 3 and REM sleep in order to “catch up.”

During slow wave sleep the majority of muscle growth, tissue repair, protein synthesis and growth hormone release take place. In addition, the most recent research suggests that during sleep, brain cells may be discarding the cellular waste products that have accumulated during a busy day of thinking and coordinating all of our body’s functions. The analogy given is that of businesses in a large city putting their garbage out at the curbside to be taken away during the night so that normal business can resume the next day.

So how much sleep do we need? It varies from person to person and by age. Children need 10 to 11 hours of sleep per night, teenagers 8 ½ to 9 ½ hours, and adults 7 to 9 hours. If we do not get enough sleep each night, we develop sleep debt. Sleep debt is like financial debt; it accumulates and needs to be repaid. In addition to sleepiness, sleep deprivation results in decreased cognitive performance, mood changes, alterations in metabolism, and creates stress on the body as a whole. As a nation we are severely sleep deprived. In a recent national poll, a third of adults reported sleeping 6 or less hours per night. Sleep debt also occurs when sleep is fragmented or broken up. There are more than 50 described sleep disorders, many of which can fragment sleep. Examples are obstructive sleep apnea, insomnia, periodic limb movement disorder and restless leg syndrome.

Sleepiness is a major safety factor for each of us, with sleepy driving being a primary concern. There are over 100,000 accidents annually in the United States due to sleepiness, 51 person of adults report driving while drowsy, and 37 percent of drivers fell asleep at the wheel once in the last year. Eight percent of commercial bus drivers report falling to sleep once or more per month and fifty percent of large truck accidents are attributed to sleepiness. Then there are the large scale disasters of which there is a long list. Just a few examples include Chernobyl, Three Mile Island, the Exxon Valdez, and the Staten Island Ferry accident, which have all been attributed to issues with sleepiness.

The stress of poor or inadequate sleep is now clearly associated with medical disorders such as obesity, coronary artery disease, adult onset diabetes, hypertension, stroke, heart arrhythmia, heart attack, depression, decreased libido/sex drive, low testosterone levels, having to urinate at night, metabolic syndrome, poor immune system function, shorter life expectancy with congestive heart failure, difficulties with cognitive function, increased frequency of Alzheimers, asthma, increased risk for some cancers (breast cancer risk imcreases 30 percent), disruptive snoring, and indigestion.

Good sleep is vital for good health. If you are having difficulties with your sleep, discuss your symptoms with your doctor and seek out help.

(David Picard is a sleep physician at Concord Hospital and medical director of the Concord Hospital Sleep Center, where he has been practicing for 20 years.)