How many hours of sleep do adults actually need?

Most adults need 7 to 9 hours of sleep per night, according to the National Sleep Foundation and the CDC. This range applies to adults aged 18 to 64, while older adults 65 and up may do well with 7 to 8 hours. These are genuine biological requirements, not suggestions you can routinely ignore. The idea that some people can thrive on 5 or 6 hours is largely a myth. Research shows that people who chronically undersleep often lose the ability to accurately judge how impaired they are. True short sleepers who function well on less than 6 hours exist but are extremely rare, estimated at less than 3 percent of the population, and it appears to be genetic.