By age · Adult (18–64 yr)
How much sleep do adults (18–64 years) need?
The 7–9 hour adult range is supported by mortality, cognitive, and metabolic outcome data. Below 6 hours chronically is associated with measurable harm.
Recommended
7–9 hrs
Cycles per night
5–6
Source
CDC 2022
What this means in practice
The 7–9 hour range is the consensus from large meta-analyses, not a strict cutoff. Individuals at the edges of the band are usually fine. Chronic sleep below the lower bound is where measurable harm appears in cognitive, metabolic, and immune endpoints.
Use our sleep calculator to translate the recommended hours into a bedtime that ends a full 90-minute cycle.