To experience optimal benefits, you need the right amount of sleep—every night. How much sleep depends on individual factors, including your age, health, and even DNA. The National Sleep Foundation provides recommended sleep duration guidelines by age, based on scientific research conducted over two years by 18 different sleep experts. Their verdict: Adults between 18 and 64 years old should get seven to nine hours of sleep every night. (The CDC recommends “seven or more hours per night” for the same age range.) Newborns and infants need the most sleep to optimize postnatal development: 14 to 17 hours, and 12 to 16 hours; respectively. There’s also scientific validation for teenagers’ notoriously heavy sleeping habits: 14- to 17-year-olds need a solid eight to 10 hours of sleep per 24 hours. (So let them sleep!) Starting around age 65, older adults only require seven to eight hours, so not quite as much as they may need in early and middle adulthood. Some adults find seven hours to be a perfectly sufficient amount of sleep, while others need closer to nine (maybe even 10) hours to feel fully rested. And remember, while some people may pride themselves on being able to function on five or six hours of sleep, the truth is, they’re likely severely sleep-deprived without realizing it. The effects of insufficient sleep can be immediate, but can also accumulate gradually and manifest in myriad health problems. In his book Why We Sleep: Unlocking the Power of Sleep and Dreams; Matthew Walker, PhD, a professor and director of UC Berkeley’s Sleep and Neuroimaging Lab, describes scientific research that concluded sleeping for only six hours a night for 10 days can make you as impaired as someone who has been awake for 24 consecutive hours. Another sleep study found that losing just 16 minutes of sleep can be detrimental to alertness and concentration—so imagine what regularly losing hours of sleep could do. Here’s a full breakdown of how much sleep you need at every age, straight from the National Sleep Foundation’s published research. When in doubt, adults should aim for seven to nine hours of shut-eye to stay as happy and healthy as possible. But speak to your doctor or a sleep specialist if you’re worried about chronic sleep deprivation or other sleep disorders keeping you from getting the rest you need and deserve.

Newborns (0 to 3 months): 14 to 17 hours each dayInfants (4 to 11 months): 12 to 15 hoursToddlers (1 to 2 years): 11 to 14 hoursPreschoolers (3 to 5): 10 to 13 hoursSchool-age children (6 to 13): 9 to 11 hoursTeenagers (14 to 17): 8 to 10 hoursYounger adults (18 to 25): 7 to 9 hoursAdults (26 to 64): 7 to 9 hoursOlder adults (65 and older): 7 to 8 hours