By: Joann Bally CSCS

Why do we need to sleep? We can give answers in two categories. First, what do we think happens physiologically during sleep? Second, what happens to us in a practical way if we don’t get enough sleep?

We don’t really know why we need sleep, but we do know that bodily functions slow down. Sleep is a state of unconsciousness, and most cognitive functions take a break. The brain may be taking this opportunity to collect, arrange, and store new information it gathers during the day. The REM stage of sleep is associated with sorting and discarding, as in when you defrag the hard drive on your computer to make more memory space. The immune system is active, and blood flow to the muscles helps restore their energy for the next day.

Sleep deprivation can cause or contribute to serious illness. Lack of sleep has been associated with high blood pressure, increased risk of stroke, and impaired glucose control in diabetics, as well as the possibility it may be a factor in the development of diabetes. Extreme sleep deprivation leads to psychological problems.

Recent research has discovered a link between lack of sleep and obesity. Though it may seem that staying awake would mean expending more calories, that doesn’t seem to be a factor. The theory that people eat more if they stay awake longer doesn’t pan out either. The cause seems to be hormonal disruption of metabolism caused by a disruption in the normal sleep cycle.

Sleepiness is a major cause of accidents. Lack of attention due to fatigue and falling asleep are implicated in almost as many traffic accidents as alcohol is. Fatigue is the major cause of 30-40% of truck accidents. Major disasters such as those as Chernobyl and Bhopal, as well as the near disaster at 3-Mile Island, have been linked to worker fatigue at early morning hours.

If you don’t get enough sleep, you will not do well on tasks that involve memory. Your disposition will suffer and you may fall asleep at inappropriate times, like social events. There is a homeostatic drive for sleep, and if it catches up with you, you fall asleep.

There is a tendency for people to think they are just too busy to sleep 7-8 hours a day. Their work is too important. Sleepiness is seen as being close to laziness. A recent Institute of Medicine report says otherwise health-conscious people are considering sleep to be an “expendable luxury.” It’s not.