•The amount of sleep that a healthy individual needs is largely determined by two factors: genetics and age. Genetics plays a role in both the amount of sleep a person needs, as well as his or her preference for waking up early (these are the so-called "larks," or morning-type individuals) or staying up late (these are the "owls," or evening-type people). Our internal biological clock, which regulates the cycling of many functions including the sleep/wake cycle, can vary slightly from individual to individual. Although our internal clock is set to approximately 24 hours, if your clock runs faster than 24 hours, you tend to be a "lark" and wake up early; if your clock runs more slowly, you tend to be an "owl" and go to bed later.
The majority of healthy adults require between 7.5 to 8.5 hours per 24-hour period. This is true from young adulthood through late in life, though many older people have difficulty sleeping in a single block of time each night. Generally, sleep needs during a 24-hour period follow this pattern: •Newborns (1 to 2 months) – 10.5 to 18 hours
•Infants (3 to 11 months) – 10 to 14 hours
•Toddlers (1 to 3 years) – 12 to 14 hours
•Preschoolers (3 to 5 years) – 11 to 13 hours
•School-aged children (5 to 12 years) – 10 to 11 hours
•Adolescents (12 to 18 years) – 8.5 to 9.5 hours
•Adults (18 years to the end of life) – 7.5 to 8.5 hours 1
Even without considering genetics and age, the National Sleep Foundation's 2008 Sleep in America poll found that many adults are apparently not meeting their sleep needs, sleeping an average of only 6 hours and 40 minutes during the week, and about 7.5 hours on the weekends.2 How can you tell if your sleep is adequate and meets your needs? Sleep scientists and physicians have a variety of methods to help identify if you are getting enough sleep. Pay attention to your sleepiness - Sleep needs and patterns of sleep and wakefulness are not the same for everyone. The first step...