Most adults need 7 to 9 hours of sleep per night. That range holds from your mid-twenties through old age, though the amount that feels right for you personally can fall anywhere within it. Children and teenagers need considerably more, and the specific target shifts several times between infancy and adulthood.
Recommended Sleep by Age
Sleep needs are highest in infancy and gradually decrease through childhood. Here are the current guidelines:
- Babies (4 to 12 months): 12 to 16 hours per day, including naps
- Toddlers (1 to 2 years): 11 to 14 hours per day
- Preschoolers (3 to 5 years): 10 to 13 hours per day
- School-age children (6 to 12 years): 9 to 12 hours per day
- Teenagers (13 to 18 years): 8 to 10 hours per night
- Adults (18 and older): 7 to 9 hours per night
For newborns under 4 months, sleep patterns vary too widely to set a single target. Some sleep as little as 11 hours, others as many as 19.
Older Adults Don’t Need Less Sleep
A common belief is that you need less sleep as you get older. That’s not true. Adults over 65 still need 7 to 9 hours, just like younger adults. What changes is the ability to get that sleep in one unbroken stretch.
As you age, sleep tends to become lighter and shorter. You may fall asleep earlier, wake up earlier, and stir more often during the night. The total time spent in the deepest, most restorative phases of sleep shrinks. So the need stays the same, but the efficiency drops, which is why many older adults feel less rested even when they spend plenty of time in bed.
The Cognitive Sweet Spot
Getting too little sleep dulls your thinking, but interestingly, sleeping too long may do the same. Research from Washington University School of Medicine found a U-shaped relationship between sleep duration and cognitive sharpness. People who reported sleeping roughly 5.5 to 7.5 hours per night maintained stable cognitive scores over time, while those sleeping significantly less or more showed faster decline.
That doesn’t mean 6 hours is ideal for everyone. The study tracked cognitive change over time in older adults, not peak performance in younger ones. But it does reinforce that there’s a real sweet spot, and oversleeping isn’t automatically better. If you consistently sleep 9 or 10 hours and still feel groggy, that may be worth paying attention to, since it can signal an underlying sleep disorder or other health issue rather than a sign you simply need more rest.
What Happens When You Don’t Get Enough
A single bad night makes you foggy, irritable, and slower to react. Chronic sleep deprivation, the kind that builds up over weeks and months of consistently short nights, carries much steeper consequences. It increases the likelihood of developing heart disease, type 2 diabetes, obesity, dementia, and several types of cancer.
The effects reach beyond your health. A RAND Corporation analysis estimated that insufficient sleep costs the U.S. economy up to $411 billion per year and roughly 1.23 million lost working days annually. Japan loses around 604,000 working days per year to the same problem. These aren’t just numbers about national productivity. They reflect millions of people dragging through their days, making more mistakes, and performing below their capacity because they’re running on too little sleep.
Sleep During Pregnancy
Pregnancy doesn’t come with a separate sleep recommendation, but the need for quality rest becomes more urgent while getting it becomes harder. In the first trimester, a surge in progesterone can make you feel unusually drowsy. The second trimester often brings some relief. By the third trimester, a growing belly, frequent bathroom trips, acid reflux, restless legs, and nasal congestion from elevated estrogen can all interfere with sleep.
These disruptions matter. Women who get fewer than six hours of sleep in a 24-hour period during pregnancy face higher risks of preeclampsia, gestational diabetes, longer labors, and cesarean delivery. Prioritizing sleep during pregnancy isn’t a luxury. It has measurable effects on outcomes for both parent and baby.
Weekend Catch-Up Doesn’t Erase Sleep Debt
If you sleep five or six hours during the week and plan to make it up on Saturday and Sunday, the math doesn’t work the way you’d hope. A Harvard Health review of research on weekend recovery sleep found that even when people technically made up their lost hours on paper, their metabolic health markers looked similar to people who stayed sleep-deprived straight through the weekend. The body doesn’t treat sleep like a bank account where deposits and withdrawals balance out neatly.
A more effective approach is to add sleep during the week itself. Even 20 to 30 extra minutes per night, consistently, does more for your body than a single long weekend sleep-in. The goal is to reduce the gap between what you need and what you get on a nightly basis, not to accumulate a debt and try to pay it off in bulk.
How to Tell If You’re Getting Enough
The guidelines give you a range, but your personal need falls somewhere specific within it. Harvard Medical School’s sleep education program suggests a few practical ways to figure out where you land.
First, pay attention to daytime sleepiness. If you routinely doze off during meetings, on public transit, or while watching TV in the evening, you’re probably not getting enough sleep. Those moments of drowsiness might feel normal, but they’re your body signaling a deficit. A well-rested person can sit through a boring lecture without nodding off.
Second, try keeping a simple sleep diary for two weeks. Record when you go to bed, when you wake up, how many times you woke during the night, and how you feel in the morning and throughout the day. Patterns emerge quickly. You might discover that you feel sharp on 7.5 hours but sluggish on 7, or that your nighttime awakenings are eating into your total more than you realized.
Third, if you have the opportunity, take a “sleep vacation.” For about two weeks, go to bed at a consistent time and don’t set an alarm. Your body will likely oversleep for the first few days as it clears any accumulated debt, then settle into a natural rhythm. The amount of sleep you gravitate toward after that initial recovery period is a good estimate of your true biological need.