How it works
Sleep runs in cycles of about 90 minutes, moving from light sleep to deep sleep and dream (REM) sleep. Waking at the end of a cycle feels easier. We add about 15 minutes for the time it takes to fall asleep.
How much sleep do you need?
| Age | Recommended sleep |
|---|---|
| 6–12 years | 9–12 hours |
| 13–18 years | 8–10 hours |
| 18–60 years | 7 or more hours |
| 61–64 years | 7–9 hours |
| 65 years and over | 7–8 hours |
Tips for better sleep
- Keep the same sleep and wake time, even on weekends.
- Stop screens 30–60 minutes before bed.
- Avoid tea and coffee after mid-afternoon.
- Keep your bedroom dark, quiet and cool.
- Get morning sunlight and daily exercise.
Frequently asked questions
How many sleep cycles do I need?
Five to six cycles (7.5–9 hours) suits most adults.
Why do I wake up tired after 8 hours?
You may be waking mid-cycle, or your sleep may be broken by snoring, stress or noise. Loud snoring with tiredness can be sleep apnoea; see a doctor.
Is napping good?
A 20-minute nap or a full 90-minute cycle avoids grogginess. Avoid long naps late in the day.
Sources
- Centers for Disease Control and Prevention. About sleep. Link
- Watson NF, et al. Recommended amount of sleep for a healthy adult: a joint consensus statement of the AASM and Sleep Research Society, 2015.
Medical disclaimer: This calculator gives estimates for general information only. It is not a diagnosis or a substitute for advice from a doctor or registered dietitian. Please consult a healthcare professional before making changes to your diet, exercise or medicines, especially if you are pregnant, have a medical condition or take regular medication.
Last updated: 20 October 2026. Read our editorial policy.
