Sleep age and sleep debt, explained
Adults need 7 to 9 hours of sleep a night, and adults over 65 need 7 to 8. Both too little and too much sleep are linked to a higher risk of death: in a review of about 1.4 million people, short sleepers had a 12% higher risk and long sleepers a 30% higher risk than people sleeping around 7–8 hours. This calculator turns your sleep hours and sleep quality into a “sleep age” and works out your weekly sleep debt.
Sources: Hirshkowitz et al., Sleep Health 2015 (National Sleep Foundation) · Cappuccio et al., Sleep 2010.
How the sleep age calculator works
It starts at your calendar age and adds or removes years for three answers:
| Input | Your answer → years |
|---|---|
| Hours of sleep | 7 to 8.5 hours: 0 · under 7: +2.2 for each hour short · over 8.5: +1.6 for each extra hour |
| How you feel on waking | Refreshed −2 · OK, a bit groggy 0 · Tired, often need caffeine +2 · Exhausted +4 |
| Nights a week you sleep well | Almost every night −1 · Most nights (4–6) 0 · A couple +1.5 · Rarely +3 |
Sleep debt is the gap between your nightly sleep and 7.5 hours, times 7 nights. Sleeping 6.5 hours a night builds up 7 hours of sleep debt a week.
Worked example. A 40-year-old who sleeps 6.5 hours, wakes a bit groggy and sleeps well most nights gets a sleep age of 41 and a sleep debt of 7 hours a week.
The year values are rounded and based on the U-shaped link between sleep and mortality. They are not a clinical sleep assessment.
How much sleep do you need by age?
| Age group | Recommended hours a night |
|---|---|
| Teenagers (14–17) | 8–10 |
| Young adults (18–25) | 7–9 |
| Adults (26–64) | 7–9 |
| Older adults (65+) | 7–8 |
About 1 in 3 US adults say they usually sleep less than recommended (CDC). Needs vary from person to person, so how you feel during the day matters as much as the number of hours.
How to lower your sleep age
- Protect 7 or more hours. Each hour you add, up to 7, takes 2.2 years off your sleep age on this calculator.
- Keep a regular schedule. Going to bed and getting up at the same time, including at weekends, helps you sleep well more nights.
- Get daylight in the morning and keep the bedroom dark, cool and quiet.
- Cut caffeine after midday and alcohol close to bedtime. Alcohol can help you fall asleep but disrupts sleep later in the night.
- See a doctor about loud snoring, gasping at night or constant tiredness. These can be signs of sleep apnea, which is common and treatable.
Sleep is one of the factors in your biological age and in the full life expectancy calculator.
Sleep age FAQ
What is sleep age?
Sleep age is an estimate of how your sleep habits compare with your calendar age. Short, poor-quality sleep pushes it higher. Seven to eight and a half hours of refreshing sleep keeps it at or below your real age.
How much sleep do adults need?
Seven to nine hours a night for adults aged 18 to 64, and seven to eight hours for adults aged 65 and over, according to the National Sleep Foundation.
How do I calculate my sleep debt?
Subtract your usual nightly sleep from 7.5 hours and multiply by 7. If you sleep 6 hours a night, your sleep debt is about 10.5 hours a week.
Is too much sleep bad for you?
Regularly sleeping 9 hours or more is linked to higher mortality in studies, but this may partly reflect illness that causes long sleep. If you need much more sleep than usual, talk to a doctor.
Can you catch up on lost sleep?
Partly. An extra hour or two on a weekend can ease short-term tiredness, but it does not fully undo regular short sleep. A steady 7 or more hours every night works better.
Last reviewed: · Sources · Educational estimate, not medical advice.