Sunday, February 6, 2011

Do people really need to sleep? Why?

Since the Science Lady hasn't gotten any new QUESTIONS lately, she's doing a several part series on Sleep. First off - do people really need to sleep? YES we do. Our furry companion cats and dogs sleep, as do all mammals and birds. Insects and fish don't really "sleep" like we do per se, but they sort of "zone out" and take mental rests. It seems that more social animals with larger brains require sleep. Why do we and other animals sleep? Several reasons: first, sleep provides a physical rest. It conserves energy. Our ancestors had limited food sources and had to conserve energy whenever possible, and sleep does that for us. Second, sleep gives the body opportunity to heal. Our sore muscles regenerate, the immune system fights infections, our skin cells renew themselves, etc. It gives the body a chance to "catch up" with everything we've done to it. Third, our brain is busy while we're sleeping. For adults, about 20-25% of our sleep is REM (random eye movement) sleep, and for infants, about 80% is REM sleep. REM sleep is when we have vivid dreams, and it's also thought to be critical for long-term memory formation. While we sleep, the brain sorts our memories and puts long-term memories into storage. Sleep deprived people have difficulty with short-term recall, attention, critical thinking skills, problem solving, and on and on. Sleep deprivation also elevates stress hormone levels, lowers our overall energy, causes mood problems, and overall makes us less efficient.

The current official record for sleep deprivation is held by Randy Gardner - a 17 year old who went for 11 days without sleep in 1964. Randy's case is still discussed in social psychology classes. Randy was supervised by a physician and a sleep researcher, William Dement. Randy was fairly high-functioning during the experiment, and they kept him awake using continuous games of pinball. However, Randy suffered from mood swings, loss of concentration, losing his temper, and had several hallucinations and delusions. On the fourth day he had a delusion that he was Paul Lowe winning the Rose Bowl, and that a street sign was a person. On the 11th day, when he was asked to subtract seven repeatedly, starting with 100, he stopped at 65. When asked why he had stopped, he replied that he had forgotten what he was doing. However, after 11 days of sleep deprivation, he could still speak coherently at a press conference. Randy slept for 14 1/2 hours afterward, then stayed awake for 24 hours, before resuming a normal sleep schedule. I wonder how this might have affected an older person, as a 17 year old might be able to bounce back better than most.

What about more normal sleep deprivation, such as when you get 4-6 hours of sleep per night repeatedly? You might not have hallucinations, but chronic sleep deprivation has been shown to increase moodiness,  increase stress hormones and "perceived levels of stress", drastically decrease mental performance and critical thinking skills, and also contribute to weight gain and risk of illness, including heart disease, viral infections, diabetes, etc. Next, the SL will tackle the common question: how much sleep is ideal? 

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