Most adults need 7 to 9 hours of sleep per night. That range has held steady through multiple reviews by the CDC and the National Sleep Foundation, and it remains the current recommendation in 2025. But the exact number shifts depending on your age, and the difference between getting six hours and seven is larger than most people realize.
Recommended Sleep by Age
Your sleep needs are highest at birth and gradually decrease through childhood, leveling off in adulthood. Here are the current CDC recommendations:
- Newborns (0–3 months): 14–17 hours
- Infants (4–12 months): 12–16 hours, including naps
- Toddlers (1–2 years): 11–14 hours, including naps
- Preschoolers (3–5 years): 10–13 hours, including naps
- School-age children (6–12 years): 9–12 hours
- Teenagers (13–17 years): 8–10 hours
- Adults (18–60 years): 7 or more hours
- Older adults (61–64 years): 7–9 hours
- Adults 65 and older: 7–8 hours
Notice that the adult recommendation doesn’t cap at nine hours the way it does for older adults. Some adults genuinely need closer to nine, and that’s normal. The floor, though, is firm: consistently sleeping under seven hours puts you in a range associated with real health consequences.
What Happens During Those Hours
Sleep isn’t one uniform state. Your brain cycles through distinct stages roughly every 90 minutes, and each stage does different work. About half your total sleep time is spent in light sleep, which serves as a transition between deeper stages. Deep sleep, the physically restorative phase where tissue repair and immune function ramp up, should make up about 13 to 23 percent of the night. REM sleep, the stage most associated with dreaming and memory consolidation, accounts for roughly 20 to 25 percent.
This cycling matters because you get proportionally more deep sleep in the first half of the night and more REM sleep in the second half. Cut your night short by even an hour and you’re disproportionately losing REM time, which affects learning, emotional regulation, and creativity. That’s one reason six hours can feel “fine” in the moment but still leave you cognitively impaired.
How Sleep Loss Affects Your Body and Brain
Staying awake beyond 16 consecutive hours produces measurable cognitive impairment. By the time you’ve been awake for 17 to 24 hours, your reaction time and decision-making ability decline to levels equivalent to a blood alcohol concentration of 0.05 to 0.10 percent. In many states, 0.08 is the legal limit for driving. In other words, pulling an all-nighter leaves you performing as though you’re legally drunk.
The metabolic effects are just as striking. A single night of sleeping only four hours can reduce your insulin sensitivity by about 16 percent. Insulin sensitivity is how efficiently your body processes blood sugar. A 16 percent drop means your cells are significantly worse at absorbing glucose, which over time raises your risk for type 2 diabetes and weight gain. This isn’t a cumulative effect that builds over months. It happens after one bad night.
Chronic short sleep also raises levels of hunger hormones while suppressing the hormones that tell you you’re full. This is one reason people who regularly sleep under seven hours tend to eat more calories, particularly from carbohydrate-heavy and high-fat foods.
Sleep Needs for Athletes
If you exercise regularly or play competitive sports, your body needs sleep for muscle repair and motor skill consolidation. The standard recommendation for athletes is 7 to 9 hours, same as the general population, but research suggests more can help. A well-known Stanford study tracked men’s basketball players who extended their sleep to 10 hours per night. Their sprint times improved, and their shooting accuracy went up by 9 percent for both free throws and three-point shots. That’s a meaningful performance gain from sleep alone, with no change in training.
You don’t have to be a college athlete to benefit. If you strength train, run, or do any form of intense exercise, the deep sleep stages are when your body releases the most growth hormone and repairs muscle tissue. Cutting sleep short reduces the time your body spends in those stages.
Sleep During Pregnancy
Pregnancy changes sleep needs and sleep quality in different ways across each trimester. During the first trimester, many women experience overwhelming daytime fatigue and an increased need for nighttime sleep, often disrupted by frequent bathroom trips and nausea. The second and third trimesters bring different challenges: a growing belly makes it harder to find a comfortable position, and heartburn, back pain, and leg cramps can fragment sleep throughout the night.
The baseline recommendation of 7 to 9 hours still applies, but the reality is that many pregnant women need to spend more time in bed to actually accumulate enough sleep, given how often they wake. Prioritizing rest and adjusting your schedule to allow for longer sleep windows becomes more important as pregnancy progresses.
How to Tell If You’re Getting Enough
The simplest test: if you need an alarm clock to wake up on workdays, you’re probably not sleeping enough. Other signs of insufficient sleep include feeling drowsy during sedentary activities like reading or watching TV, needing caffeine to function in the afternoon, and falling asleep within five minutes of lying down (which signals sleep debt, not “being a good sleeper”).
For a more structured self-assessment, the Epworth Sleepiness Scale is a quick questionnaire used by sleep clinicians. It asks you to rate how likely you are to doze off in eight common situations, like sitting and reading or watching TV. A score of 0 to 10 is considered normal. Scores of 11 to 14 indicate mild sleepiness, 15 to 17 suggest moderate sleepiness, and 18 or higher points to severe sleepiness that warrants professional evaluation. You can find the questionnaire online through Harvard Medical School’s sleep division.
Naps Can Help, but Timing Matters
Napping doesn’t replace a full night of sleep, but short naps can partially offset a bad night. The key is keeping them short. Naps of about 10 to 20 minutes improve alertness without leaving you groggy afterward. Once a nap stretches to 30 minutes or longer, you risk entering deep sleep, and waking from deep sleep produces sleep inertia: that heavy, disoriented feeling that can linger for up to an hour.
Timing also matters. Napping after about 3 p.m. can interfere with your ability to fall asleep at night, creating a cycle where you sleep poorly, nap late, then sleep poorly again. If you’re going to nap, early afternoon is the sweet spot for most people.
Quality Matters as Much as Quantity
Seven hours of fragmented sleep is not the same as seven hours of uninterrupted sleep. The National Sleep Foundation’s 2025 survey found that people who consistently hit the recommended duration were more likely to report flourishing overall well-being (66 percent) compared to those who didn’t (57 percent). But duration was only part of the picture. Sleep quality, meaning how consolidated and uninterrupted your sleep is, played an equally important role.
A few practical factors that protect sleep quality: keeping your bedroom cool (around 65 to 68°F works for most people), limiting screen exposure in the hour before bed, and going to sleep and waking at roughly the same time every day, including weekends. Consistency in your sleep schedule helps regulate your circadian rhythm, making it easier to fall asleep and improving the proportion of time you spend in restorative deep and REM stages.