For most healthy adults, seven to nine hours of sleep a night supports good physical and mental health. Some people feel fine on slightly less and a few need a little more, but regularly getting under about seven hours is linked to problems with mood, concentration, immunity, and long-term health. Older adults often sleep a bit less and more lightly, which can be normal.
Children and teenagers need more: school-age children typically need nine to eleven hours, and teenagers around eight to ten. Consistency matters too. Going to bed and waking at similar times each day, including weekends, helps your body clock and improves sleep quality.
Rather than fixating on a number, notice how you feel during the day. Waking unrefreshed, relying on caffeine, or feeling sleepy in the afternoons can signal you are not getting enough good-quality sleep. If you sleep enough hours but still feel exhausted, or you snore heavily and wake gasping, see a doctor to check for conditions such as sleep apnoea.