Sleep Across the Lifespan

Infants and small children need dramatically more total sleep because their brains are laying down foundational architecture at a pace no other stage matches. Adolescents’ circadian rhythm shifts later, which is why early school start times so reliably produce under-slept teenagers. Adults settle into a roughly seven-to-nine hour range with more variability. Older adults often need similar total sleep but distribute it differently — lighter, more fragmented, sometimes with an earlier bedtime and earlier wake time.

At every age, sleep is where memory consolidates, emotion is processed, tissue repairs, and the nervous system’s window of tolerance is restored. The mechanisms are stable across the lifespan. What changes is the schedule and the total hours required. What stays constant is the requirement for a rested system.

Rather than measuring against a single ideal, a person can ask a more useful question: what does adequate sleep look like for this nervous system, at this age, under these current demands? That question, honestly answered, tends to point toward a schedule the person can actually keep — which matters more than any theoretical target.