How much sleep do you actually need?

The American Academy of Sleep Medicine recommends 7+ hours nightly for adults 18–60. Below 7 hours and disease risk rises measurably (cardiovascular, metabolic, immune). Above 9 hours, mortality risk also rises — though this likely reflects underlying health conditions causing oversleep, not the sleep itself.

Mutations in DEC2, ADRB1, and NPSR1 produce genuine short sleepers who function on 4–6 hours with no detectable cost. They make up <1% of the population. If you think you're one — you're almost certainly not.

Self-reported short sleepers who use stimulants, struggle to wake up, or feel groggy in afternoons aren't true short sleepers; they're sleep-deprived.