University at Buffalo - The State University of New York

• Print

• Comments

• 

Published: April 21, 2011

The answer to that question is simple. We all do. Sleep is fundamental to our health and well-being, it affects our daily lives in ways that researchers are only beginning to understand.

According to the National Institute of Neurological Disorders and Stroke (NINDS), humans usually pass through five stages of sleep: stages 1, 2, 3, 4 and REM (rapid eye movement).

During stage 1, which is light sleep, we drift in and out of sleep and can be awakened easily. Our eyes move very slowly and muscle activity slows.

At stage 2, our eye movements stop and our brain waves become slower, with occasional bursts of rapid waves.

In stage 3, extremely slow brain waves, called delta waves, begin to appear, interspersed with smaller, faster waves.

By stage 4, the brain produces delta waves almost exclusively. It is very difficult to wake someone during stages 3 and 4, which together are called deep sleep. There is no eye movement or muscle activity. People awakened during deep sleep do not adjust immediately and often feel groggy and disoriented for several minutes after waking up.

When we move into REM sleep, breathing becomes more rapid, irregular and shallow, our eyes jerk rapidly in various directions and limb muscles become temporarily paralyzed. The heart rate increases and our blood pressure rises. When people awaken during REM sleep, they often describe bizarre and illogical tales—dreams.

People awakened after sleeping more than a few minutes usually are unable to recall the last few minutes before they fell asleep. This sleep-related form of amnesia is the reason people often forget telephone calls or conversations they’ve had in the middle of the night. It also explains why we often do not remember our alarms ringing in the morning if we go right back to sleep after turning them off.

While the reasons humans need sleep remain largely unknown, animal studies have indicated that sleep is essential for survival. NINDS also reports that rats deprived of REM sleep can die in as little as three weeks. As for humans, lack of sleep, according to the Centers for Disease Control and Prevention, can lead to chronic illnesses such as diabetes, cardiovascular disease, obesity and depression.

Additionally, the National Sleep Foundation reports that lack of sleep can lead to decreased functioning of the immune system. Chronic sleep loss can lead to increased susceptibility to infectious diseases, including cold and flu.

On a more shallow level, sleep deprivation can affect your physical appearance. In December 2010, an ABC News report highlighted the connection between sleep and appearance.

There are several easy things that you can do every day to improve sleep. The American Academy of Sleep Medicine (AASM) recommends practicing good sleep hygiene and offers numerous tips. (for a complete list of sleep hygiene tips, visit the AASM’s website) Among them:

• Don’t go to bed unless you’re sleepy.
• If you are not asleep after 20 minutes, then get out of bed.
• Begin rituals that help you relax each night before bed.
• Get up at the same time every morning.
• Don’t read, write, eat, watch TV, talk on the phone or play cards in bed.
• Do not have any caffeine after lunch.
• Do not have a beer, a glass of wine or any other alcohol within six hours of bedtime.
• Avoid strenuous exercise within six hours of bedtime. You should exercise on a regular basis, but do it earlier in the day.
• Make your bedroom quiet, dark and a little bit cool.

For information about sleep, the University Libraries has more resources, including the database MEDLINE, CINAHL and PsycINFO.

A Few Sleep Facts from the National Sleep Research Project:

• The European Court of Human Rights has ruled that sleep deprivation is a form of torture.
• Most of what we know about sleep we’ve learned in the past 25 years.
• Teenagers need as much sleep as small children—about 10 hrs—while those over 65 need the least of all—about six hours. For the average adult aged 25-55, eight hours is considered optimal.
• After five nights of partial sleep deprivation, three alcoholic drinks will have the same effect on your body as six would when you’ve had enough sleep.
• Dreams may not serve any purpose at all, but be merely a meaningless byproduct of two evolutionary adaptations—sleep and consciousness.
• Elephants sleep standing up during non-REM sleep, but lie down for REM sleep.
• A new baby typically leads to 400-750 hours of lost sleep for parents in the first year

—Linda Hasman, Health Sciences Library