The amount of sleep a person needs depends on many factors, including age. In general:
- Infants require about 12-15 hours a day
- Toddlers require about 11-14 hours a day.
- Pre-school children require 10-13 hours a day.
- School-age children require 9-11 hours a day.
- Teenagers need about 8.5-9.5 hours on average.
- Most adults need 7 to 9 hours a night for the best amount of sleep, although some people may need as few as 6 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.
However, experts say that if you feel drowsy during the day, even during boring activities, you haven't had enough sleep.
Sleep Debt
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.
Consequences of Too Little Sleep
Too little sleep may cause:
- Memory problems
- Depression
- A weakening of your immune system, increasing your chance of becoming sick
- Increase in perception of pain
Dangers of Sleep Deprivation
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 83,000 motor vehicle accidents and about 850 deaths each year, according to the
National Highway Traffic Safety Administration. Some researchers, though, believe the numbers are actually much higher. 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 you are probably too drowsy to drive safely if you:
- Have trouble keeping your eyes focused
- Can't stop yawning
- Can't remember driving the last few miles
- Are daydreaming and have wandering thoughts
- Have trouble holding your head up
- Are drifting in and out of lanes