Sleep needs change across life: newborns need 14–17 hours, toddlers and preschoolers 10–14 hours, school-age kids 9–12 hours, teens 8–10 hours, and adults at least 7 hours, per the CDC. There is no single number for everyone — but falling under these ranges night after night raises health risks.
Search for "how much sleep do I need" and you will run into the old rule of thumb: eight hours, every night, no exceptions. That number is not wrong exactly, but it is incomplete. Sleep need is not one figure — it is a range that shifts dramatically with age, and even within an age group it varies from person to person. This guide breaks down recommended sleep by age, from newborns through older adults, using the age-based framework published by the CDC, and explains what the research says about why hitting your range matters.
For adults ages 18 to 60 and older, the CDC recommends at least 7 hours of sleep per night. That is a floor, not a fixed target — some adults function well on 7 hours, others need closer to 9, since sleep need is polygenic and roughly normally distributed across a range of about 6.5 to 8.5 hours rather than locked to a single number for everyone.
The data on why 7 hours matters as a minimum comes from large studies of sleep duration and mortality, which show a U-shaped relationship: risk is lowest around 7–8 hours, rises for people who consistently sleep under 7 hours (hazard ratio ≈1.14), and rises again for those who sleep 9 hours or more (hazard ratio ≈1.34). The long-sleep end of that curve is thought to reflect underlying illness driving both the extra sleep and the added risk, rather than long sleep itself causing harm.
Falling short of 7 hours has measurable effects even after a single week. Restricting sleep to about 5 hours a night for one week has been shown to lower peripheral insulin sensitivity by up to 16% and reduce testosterone in young men by 10–15%. Short sleep also shifts appetite hormones — leptin drops roughly 18% and ghrelin rises roughly 28% — which in studies translated to about 385 extra calories consumed per day. Immune function takes a hit too: people sleeping under 7 hours had close to a 2.94-times higher risk of catching a cold than those sleeping 8 hours or more.
One counterintuitive finding: getting 6 hours a night for two straight weeks produces cognitive performance deficits comparable to two full nights of total sleep deprivation, even though people in that state often report feeling only mildly tired. And sleeping in on weekends helps restore day-to-day alertness, but it does not undo the metabolic and inflammatory buildup from a week of short sleep — the research does not support alcohol as a sleep aid either, since it suppresses REM sleep and fragments the second half of the night. If you are consistently falling short, practical strategies for how to sleep better or an evaluation for insomnia are reasonable next steps.
Older adults are sometimes told they need less sleep. That is a myth: the recommended range stays at 7–8 hours throughout adulthood. What changes with age is the brain's ability to generate deep, slow-wave sleep, which can make sleep feel lighter even though the underlying need has not dropped.
Teenagers ages 13 to 18 need 8 to 10 hours of sleep per night, according to the CDC. That is roughly two hours more than the adult minimum, and it is not an arbitrary buffer — deep, slow-wave sleep is when the brain releases the most growth hormone and carries out tissue repair, while REM sleep supports the emotional processing that adolescence puts a heavy demand on.
A 13-year-old falls at the younger edge of the CDC's teen category (13–18 years) and needs the same 8 to 10 hours as the rest of that range. There is no separate CDC figure that carves out early teens from older teens — the recommendation applies across the full 13–18 span.
Sleep needs for kids vary noticeably even within childhood. The CDC recommends 10 to 13 hours for preschoolers ages 3 to 5, and 9 to 12 hours for school-age children ages 6 to 12. Toddlers ages 1 to 2 need slightly more, at 11–14 hours.
The deep, slow-wave stage of sleep (N3) is where the body releases the most growth hormone and carries out tissue repair, which is one reason pediatric sleep guidance skews toward longer totals than adult guidance — growing bodies are doing more repair work overnight.
A 3-year-old falls in the CDC's preschool category (ages 3–5) and needs about 10 to 13 hours across a 24-hour day, which can include a daytime nap in addition to nighttime sleep.
The CDC's sleep recommendations are not broken out by sex — the guideline for adult women, like adult men, is at least 7 hours per night for ages 18 and up. There is no separate CDC or NHLBI figure specifically for women's baseline sleep need; the general adult range applies. What can differ is sleep quality at various life stages (for example, hormonal shifts can affect how restorative sleep feels), but the underlying hours-needed target does not change based on sex according to the sources behind this guide.
The table below lays out the full CDC breakdown in one place — sometimes searched as sleep requirements by age, recommended sleep by age, or sleep needs by age. All figures are total sleep across a 24-hour day, including naps for infants and young children.
Zooming out from any single age group, the honest answer to "how many hours of sleep do we need" is: it depends on age, and even within an age group it is a range rather than one fixed number. Sleep is governed by two interacting systems — a homeostatic drive that builds up the longer you are awake (tracked biochemically by adenosine accumulation), and a circadian rhythm run by the brain's master clock, the suprachiasmatic nucleus. Together these two processes set both when you feel sleepy and roughly how much sleep your body is pushing you toward getting.
Population data on adults backs up the "not one number" idea directly: total mortality risk traces a U-shape across reported sleep duration, bottoming out around 7–8 hours and rising on both the short and long side. That is the strongest evidence that the old blanket "everyone needs 8 hours" rule oversimplifies things — the CDC's age-by-age ranges are the more accurate framework, with 7+ hours as the adult floor rather than a universal target.
Newborns ages 0 to 3 months need about 14 to 17 hours of sleep across a 24-hour day, spread across many short stretches rather than one continuous block. Infants ages 4 to 12 months need somewhat less, at 12 to 16 hours including naps, per the CDC.
Alongside how much a newborn sleeps, how they sleep matters for safety. The CDC recommends always placing babies on their back to sleep (through age 1), on a firm, flat surface, never on a couch or sitting device. Room-sharing without bed-sharing — keeping the baby's sleep space in the parents' room but not in the parents' bed — is associated with up to a 50% reduction in SIDS risk. Since the "Safe to Sleep" campaign launched in 1994, SIDS incidence has dropped by more than 50%. Any ongoing concerns about a newborn's breathing or sleep patterns are worth raising directly with a pediatrician.
Coming back to teens with a closer look: the CDC's target of 8 to 10 hours for ages 13–18 is the range to aim for, but several everyday habits make it harder for teens to actually reach it. Caffeine is one — its average half-life is around 5 hours (ranging 1.5–9.5 hours depending on genetics), so even a caffeinated drink consumed 6 hours before bed can measurably disrupt sleep, and that includes soda or energy drinks common in teen routines.
Evening light exposure is another factor. Light — especially blue light around 480 nm — is the primary signal the brain uses to time sleep, detected by light-sensitive cells in the retina that feed directly into the circadian clock. Bright artificial light at night, including from phone and laptop screens, suppresses melatonin and can push a teen's natural sleep timing later, making an 8–10 hour night harder to fit before an early school start. Consistent bedtimes and screen limits before sleep are among the most direct ways to close that gap — see how to sleep better for more on building that routine.
Sleep needs vary, but some signs point to a problem worth medical evaluation rather than just "needing more sleep":
These situations call for a clinician's evaluation rather than self-diagnosis — this article does not provide medical advice.