How Many Hours of Sleep Do You Need?
The amount of sleep a person needs depends on many things, including their age. In general:
Infants (ages 0-3 months) need 14-17 hours a day.
Infants (ages 4-11 months) need 12-15 hours a day
Toddlers (ages 1-2 years) need about 11-14 hours a day.
Preschool children (ages 3-5) need 10-13 hours a day.
School-age children (ages 6-13) need 9-11 hours a day.
Teenagers (ages 14-17) need about 8-10 hours each day.
Most adults need 7 to 9 hours, 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.
But experts say that if you feel drowsy during the day, even during boring activities, you haven't had enough sleep.
Sleep Deprivation and Sleep Debt
The amount of sleep a person needs goes up if they’ve missed sleep on previous days. If you don’t have enough, you’ll have a "sleep debt," which is much like being overdrawn at a bank. Eventually, your body will demand that you start to repay the debt.
We don't really adapt to getting less sleep than we need. We may get used to a schedule that keeps us from getting enough sleep, but our judgment, reaction time, and other functions will still be off.
Why You Need REM Sleep and Deep Sleep
There are four stages of sleep, based on how active your brain is. The first two are light.
Stage three is “deep sleep,” when your brain waves slow down and it’s harder for you to wake up. During these periods, your body repairs tissues, works on growth and development, boosts your immune system and builds up energy for the next day.
Rapid eye movement (REM) sleep, or stage R, usually starts about 90 minutes after you fall asleep. Brain activity increases, your eyes dart around quickly, and your pulse, blood pressure, and breathing speed up. This is also when you do most of your dreaming.
REM sleep is important for learning and memory. It’s when your brain handles information you’ve taken in during the day and stores it in your long-term memory.
Credit: WebMD Medical Reference Reviewed by Brunilda Nazario, MD