Do Adults Really Need 7 to 9 Hours of Sleep a Night?

Do Adults Really Need 7 to 9 Hours of Sleep a Night?

Yes, for most healthy adults. The National Sleep Foundation recommends 7 to 9 hours for young adults and adults, and 7 to 8 hours for older adults. A 2026 review of 133 meta-analyses found none that contradicted those ranges, and large studies link regularly sleeping too little with higher risk of early death, diabetes and heart disease.

The 7 to 9 hour figure is not a single study result. It is the judgment of an expert panel that read the research and voted. Ten years later, the evidence still points to the same place: the lowest health risk sits at about 7 hours, and risk climbs on both sides of the range.

What the Data Show

In 2015 the National Sleep Foundation (NSF) brought together an 18-member panel from 12 organizations. The panel reviewed the published research on sleep and health, then used a structured voting method called the RAND/UCLA Appropriateness Method. For healthy people without a sleep disorder, the panel settled on 7 to 9 hours for young adults and adults and 7 to 8 hours for older adults.

The final report sorted sleep times for 9 age groups into three bands: recommended, may be appropriate, or not recommended. So 7 to 9 hours is the target, and a little outside it can still be fine for some people.

In 2026 the NSF checked its own work. A systematic review of 133 meta-analyses published over the previous decade found that 74% supported the recommendations and 26% were inconclusive. None contradicted them, for short sleep or long sleep. Most of those analyses found no real difference between men and women. The authors concluded that the review “re-certifies” the ranges.

The CDC lines up with this. It states that adults aged 18 to 60 should sleep at least 7 hours a night.

Sleep Recommendations by Age

The NSF panel set these recommended ranges, in hours per day:

These are for healthy people. Someone with sleep apnea, insomnia or another sleep disorder needs that problem treated, not just more time in bed.

Do Young Adults 18 to 25 Need 7 to 9 Hours Too?

Yes. The NSF gives young adults the same 7 to 9 hour range as other adults.

The lab studies that show what short sleep does were mostly run in young, healthy people. In one, healthy adults aged 21 to 38 were assigned to 4, 6 or 8 hours in bed for 14 days. Both the 4-hour and 6-hour groups got steadily worse on every thinking test. Six hours or less a night for two weeks caused deficits equal to up to 2 nights of no sleep at all.

When young adults are given as much time in bed as they want, they tend to sleep longer than 7. In an inpatient study, younger healthy adults settled at about 8.9 hours a day once the extra sleep had worn off.

What Happens If You Sleep Less Than 7 Hours?

About 1 in 3 US adults reports sleeping under 7 hours, according to a CDC survey of 444,306 people.

Death from any cause. A 2025 meta-analysis of 79 cohort studies found that sleeping under 7 hours was tied to about 14% higher risk of death compared with 7 to 8 hours. A cohort study follows a large group of people over years to see who gets sick. A dose-response analysis found the lowest risk at about 7 hours a night, with risk of death about 6% higher for each hour below that.

Diabetes, blood pressure, heart disease and weight. A meta-analysis of 153 studies with over 5 million people linked short sleep with about 37% higher risk of type 2 diabetes, 38% higher risk of obesity, 26% higher risk of coronary heart disease (blocked heart arteries), 17% higher risk of high blood pressure, 16% higher risk of cardiovascular disease overall, and 12% higher risk of death.

In that analysis, the rise in death risk became clear below 6 hours.

Thinking and reaction time. In the 14-day experiment above, people sleeping 6 hours rated themselves only a little sleepy, yet they were largely unaware of how much their performance had dropped. In another trial, 66 volunteers spent 3, 5, 7 or 9 hours in bed for a week. Reaction speed slowed even in the 7-hour group and then held at that lower level. Only the 9-hour group stayed at their starting level. Note that these were hours in bed, and people sleep somewhat less than the time they spend in bed.

These cohort links do not prove that short sleep causes disease, but the lab and population findings point the same way.

Is Sleeping More Than 9 Hours Bad for You?

Long sleep carries risk too, but the cause is less clear. In the 2025 meta-analysis, sleeping 9 hours or more was tied to about 34% higher risk of death than 7 to 8 hours. The effect of long sleep was stronger in women. The dose-response analysis found risk of death about 13% higher for each hour above 7.

A meta-analysis of 137 studies linked long sleep with about 39% higher risk of death, 46% higher risk of stroke, and 26% higher risk of diabetes. It found no link with high blood pressure. The authors said future studies need to work out whether long sleep is a cause or something that can be changed.

That question matters. Many illnesses, such as depression, heart failure and sleep apnea, make people sleep longer or spend more time in bed. So long sleep may often be a sign of a problem rather than the problem itself. The NSF panel made the same point: people who regularly sleep far outside the normal range may be showing signs of serious health problems.

Do Older Adults Need Less Sleep?

A little less. The NSF sets 7 to 8 hours for older adults, against 7 to 9 for younger adults.

The best evidence that this is biology, not just habit, comes from an inpatient study of 18 older and 35 younger healthy adults. Each person was given 16 hours a day of sleep opportunity (12 at night and 4 in the afternoon) for several days. Once their sleep settled, the older adults slept about 7.4 hours and the younger adults about 8.9, a 1.5-hour gap. The authors concluded that the maximum capacity for sleep falls with age.

This does not mean older adults can get by on 5 or 6 hours. It means the target narrows to 7 to 8. Broken sleep, waking too early, and daytime sleepiness in an older adult are worth looking into rather than writing off as normal aging.

Can You Catch Up on Sleep on the Weekend?

Not fully. In a randomized trial, healthy young adults slept 5 hours a night through the workweek. One group then slept as long as they liked on the weekend. They got back only about 1.1 extra hours in total. When the short nights resumed, their insulin sensitivity (how well the body responds to insulin to clear sugar from the blood) fell about 9% to 27% below their starting level. The group with no weekend catch-up lost about 13% on the main measure. The authors concluded that weekend recovery sleep did not prevent the metabolic harm.

The week-long reaction time trial points the same way. After a week of 5 or 7 hours in bed, 3 nights of 8 hours did not bring reaction speed back to where it started.

Dr. Kumar’s Take

The 7 to 9 hour range started as an expert vote, and that is a fair criticism. But the panel’s call has held up. A decade of meta-analyses has not produced a single one that contradicts it, and the lowest risk keeps landing near 7 hours. I find the lab work even more convincing than the cohort numbers: people on 6 hours a night lose ground every day and do not feel it.

The part people get wrong is the long end. Sleeping 10 hours is not extra credit. When a healthy adult starts needing far more sleep than usual, that is a reason to look for a cause, such as sleep apnea, depression, a thyroid problem, or a medication side effect. Aim for the middle of the range, keep it steady through the week, and treat a big change in either direction as information.

Practical Takeaways

• Aim for 7 to 9 hours of actual sleep, or 7 to 8 if you are an older adult. Time in bed should be a bit longer than that.
• Do not trust how you feel on 6 hours. In the lab, people underrated how impaired they were.
• Keep the same schedule on weekends. Sleeping in does not undo a week of short nights.
• Treat long sleep as a signal. Regularly needing 9 hours or more, or a sudden increase, is worth a checkup.
• Older adults: 7 to 8 hours is normal. Fragmented sleep or daytime sleepiness is not, and deserves a look.
• See a doctor for loud snoring, gasping at night, or sleepiness while driving. Those point to a sleep disorder that more hours will not fix.

Related Studies and Research

• How Melatonin Timing Changes with Age: DLMO Patterns Across the Lifespan
• Sleep Stages Explained: Your Nightly Journey Through REM and NREM Sleep
• The Two-Process Model: Why You Get Sleepy When You Do
• Is Short Sleep in Midlife Linked to Higher Dementia Risk Decades Later?
• Sleep Debt Disrupts Metabolism and Hormone Function in Young Men
• One-Third of US Adults Get Less Than 7 Hours of Sleep: Geographic Patterns Revealed
• Episode 23: How to Sleep Better, The Science and Daily Playbook
• Episode 31: Depression Explained, The Biology Behind the Darkness
• Episode 32: Depression Recovery Roadmap: A Step-by-Step, Evidence-Based Plan

FAQs

How many hours of sleep does the National Sleep Foundation recommend for adults?

The National Sleep Foundation recommends 7 to 9 hours a night for young adults and adults, and 7 to 8 hours for older adults. These ranges are for healthy people without a sleep disorder. A 2026 review of the past decade of research re-certified them.

Is 6 hours of sleep enough?

For most adults, no. In a two-week lab experiment, 6 hours a night caused thinking deficits equal to up to 2 nights without sleep, and people did not notice how impaired they were.

Is it bad to sleep 10 hours?

Regularly sleeping 9 hours or more is linked to higher risk of death and stroke in large studies. That link may reflect illness that causes long sleep rather than harm from the sleep itself. Either way, a regular need for 10 hours is worth discussing with a doctor.

Do women need more sleep than men?

The evidence does not show a clear difference. A 2026 review found that most meta-analyses reported no meaningful sex difference, so the same 7 to 9 hour range applies to both.

Bottom Line

The National Sleep Foundation’s 7 to 9 hours for adults, and 7 to 8 for older adults, has held up for ten years. Large studies put the lowest risk near 7 hours, short sleep dulls your thinking more than you notice, and weekend sleep-ins do not repay the debt. Sleep in the range, keep it steady, and treat a big change in your sleep need as a reason to get checked.