How much sleep do adults actually need?
Short Answer
Most adults do best with about 7–9 hours per night. Some need slightly more or less, but consistently feeling alert, stable, and recovering well is the best indicator.
Why This Matters
This matters because sleep time determines how much deep sleep and REM you can accumulate, which leads to better learning, emotional regulation, and physical recovery. Chronic short sleep results in attention lapses and metabolic and immune disruption even when you “get used to it.” Knowing your target helps you plan consistent bed and wake times instead of relying on weekend catch-up.
Where This Changes
Sleep quality matters as much as quantity: untreated apnea, pain, or insomnia can make 8 hours ineffective. Illness, heavy training, and stress can temporarily increase needs, and older adults often sleep lighter even if their total need changes less than people assume.