How Much Sleep Do We Need?

The amount of sleep each person needs depends on many factors, including age.
Infants generally require about 16 hours a day, while teenagers need about 9
hours on average. For most adults, 7 to 8 hours a night appears to be the best
amount of sleep, although some people may need as few as 5 hours or as many as
10 hours of sleep each day. Women in the first 3 months of pregnancy often need
several more hours of sleep than usual. The amount of sleep a person needs also
increases if he or she has been deprived of sleep in previous days. Getting too
little sleep creates a “sleep debt,” which is much like being overdrawn at a
bank. Eventually, your body will demand that the debt be repaid. We don’t seem
to adapt to getting less sleep than we need; while we may get used to a
sleep-depriving schedule, our judgment, reaction time, and other functions are
still impaired.

People tend to sleep more lightly and for shorter time spans as they get
older, although they generally need about the same amount of sleep as they
needed in early adulthood. About half of all people over 65 have frequent
sleeping problems, such as insomnia, and deep sleep stages in many elderly
people often become very short or stop completely. This change may be a normal
part of aging, or it may result from medical problems that are common in elderly
people and from the medications and other treatments for those problems.

Experts say that if you feel drowsy during the day, even during boring
activities, you haven’t had enough sleep. If you routinely fall asleep within 5
minutes of lying down, you probably have severe sleep deprivation, possibly even
a sleep disorder. Microsleeps, or very brief episodes of sleep in an
otherwise awake person, are another mark of sleep deprivation. In many cases,
people are not aware that they are experiencing microsleeps. The widespread
practice of “burning the candle at both ends” in western industrialized
societies has created so much sleep deprivation that what is really abnormal
sleepiness is now almost the norm.

Many studies make it clear that sleep deprivation is dangerous.
Sleep-deprived people who are tested by using a driving simulator or by
performing a hand-eye coordination task perform as badly as or worse than those
who are intoxicated. Sleep deprivation also magnifies alcohol’s effects on the
body, so a fatigued person who drinks will become much more impaired than
someone who is well-rested. Driver fatigue is responsible for an estimated
100,000 motor vehicle accidents and 1500 deaths each year, according to the
National Highway Traffic Safety Administration. Since drowsiness is the brain’s
last step before falling asleep, driving while drowsy can – and often does –
lead to disaster. Caffeine and other stimulants cannot overcome the effects of
severe sleep deprivation. The National Sleep Foundation says that if you have
trouble keeping your eyes focused, if you can’t stop yawning, or if you can’t
remember driving the last few miles, you are probably too drowsy to drive
safely.