Sleep needs change significantly across a lifetime — what's healthy for a teenager is very different from what's healthy for an adult or older person.
Newborns (0-3 months)
14 to 17 hours per day, though this is typically spread across multiple shorter sleep periods rather than one continuous stretch, since newborns don't yet have a settled day-night sleep cycle.
Infants and toddlers (4 months-2 years)
Infants generally need 12-16 hours including naps, while toddlers (1-2 years) need around 11-14 hours as naps gradually become less frequent.
Children (3-13 years)
Preschoolers typically need 10-13 hours, while school-age children (6-13) generally need 9-11 hours. Consistent sleep during these years is strongly linked to attention, behavior, and learning outcomes.
Teenagers (14-17 years)
8-10 hours is the generally recommended range, though most teenagers get meaningfully less than this due to early school start times combined with a natural biological shift toward staying up later during adolescence.
Adults (18-64 years)
7-9 hours is the standard recommendation for most adults. Consistently sleeping less than 7 hours is associated with a range of negative health outcomes over time, even if it doesn't feel noticeably harmful day to day.
Older adults (65+)
7-8 hours is still generally recommended, though sleep often becomes lighter and more fragmented with age, and many older adults naturally wake earlier than they did when younger.
Why sleep cycles matter, not just total hours
Sleep happens in roughly 90-minute cycles, and waking up in the middle of a cycle — rather than between cycles — is a major reason people feel groggy even after what should be enough total sleep. Timing your wake-up to align with the end of a cycle can make a real difference to how rested you feel.
FAQ
Is it possible to get too much sleep?
Yes — consistently sleeping significantly more than the recommended range for your age has also been associated with negative health outcomes in research, though needs do vary somewhat by individual.
Why do I feel tired even after 8 hours of sleep?
Waking up in the middle of a 90-minute sleep cycle rather than at its natural end point is a common cause of grogginess, even when your total sleep duration was technically sufficient.
Do naps count toward my total sleep needs?
For young children, yes — recommended totals typically include daytime naps. For adults, naps can help offset short-term sleep debt but aren't usually counted toward the core recommended nightly range.
What are the stages of sleep and how much of the night is spent in each?
A typical night cycles through four stages — N1 and N2 (light sleep), N3 (deep, slow-wave sleep), and REM (dream sleep) — repeating every 90 minutes or so. See the breakdown above for roughly how much of a night's sleep each stage takes up.
Why does deep sleep (N3) matter even though it's a smaller share of the night?
Deep sleep is when the body does most of its physical repair — tissue growth, muscle recovery, and immune-system reinforcement — which is why it's often called the most physically restorative stage, even though it typically makes up only about a quarter of total sleep.
How many hours of sleep do adults need?
Most health organisations recommend 7 to 9 hours a night for adults aged 18 to 64, and 7 to 8 hours for those over 65. Individual needs vary within those ranges.
Can I catch up on lost sleep at the weekend?
Extra sleep at the weekend can reduce tiredness, but it may not fully reverse the effects of regular short sleep during the week. A consistent schedule is a better aim.
What time should I go to bed to get 8 hours?
Count back from your wake-up time: for a 6:00 AM alarm, lights out at 10:00 PM gives 8 hours. Add 10 to 20 minutes for falling asleep.