The amount of sleep a person needs depends on many factors, including age. In general:
Infants (ages 0-3 months) require 14-17 hours a day.
Infants (ages 4-11 months) require 12-15 hours a day
Toddlers (ages 1-2 years) require about 11-14 hours a day.
Pre-school children (ages 3-5) require 10-13 hours a day.
School-age children (ages 6-13) require 9-11 hours a day.
Teenagers (ages 14-17) need about 8-10 hours each day.
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.
Older adults (ages 65 and older)need 7-8 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.
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:
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 was responsible for an estimated 83,000 motor vehicle accidents between 2005 and 2009 and 803 deaths in 2016, 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？
WebMD Medical Reference Reviewed by Louise Chang, MD on July 02, 2018 Copy from: https://www.webmd.com/