It is one of those facts that have gone pretty much unquestioned for decades: Get 8 hours of sleep every night.  It’s a convenient starting point for adults, but not so much for older adults, children, and teens. Now, the National Sleep Foundation has updated its guidelines on how many hours of sleep people need, adding age brackets and widening the acceptable ranges of sleep every night for most existing age groups. (The NSF also added a category of sleep times that isn’t recommended, but may be appropriate for some people. A graphic that includes all of that is here.) The new recommendations, based on age, look like this: 

Newborns (0-3 months): 14-17 hours (range narrowed from 12-18)Infants (4-11 months): 12-15 hours (range widened from 14-15)Toddlers (1-2 years): 11-14 hours (range widened from 12-14)Preschoolers (3-5): 10-13 hours (range widened from 11-13)School-Age Children (6-13): 9-11 hours (range widened from 10-11)Teenagers (14-17): 8-10 hours (range widened from 8.5-9.5)Young Adults (18-25): 7-9 hours (new age category)Adults (26-64): 7-9 hours (no change)Older Adults (65+): 7-8 hours (new age category)

Struggling to get the necessary 7-9 hours each night? Read up on 6 Reasons You’re Not Getting a Good Night’s Sleep for some strategies to do better. The recommendations were made based on “multiple rounds of consensus voting after a comprehensive review of published scientific studies on sleep and health,” according to the foundation’s statement. “This is the first time that any professional organization has developed age-specific scientific literature relating sleep duration to health, performance, and safety,” said Charles A. Czeisler, PhD, MD, chairman of the board of the National Sleep Foundation, in the statement. “The National Sleep Foundation is providing these scientifically grounded guidelines on the amount of sleep we need each night to improve the sleep health of the millions of individuals and parents who rely on us for this information.” This article “New Rules for the Best Amount of Sleep at Any Age” originally ran on Menshealth.com. Feeling tired despite getting plenty of time in bed? Start with these 5 Ways to Sleep Better Every Night.