'Sleep debts' accrue when nightly sleep totals six hours or fewer

Those who believe they can function well on six or fewer hours of sleep every night may be accumulating a “sleep debt” that cuts into their normal cognitive abilities, according to research conducted at the University of Pennsylvania School of Medicine. What’s more, the research indicates, those people may be too sleep-deprived to know it. The study, published in the March 15 issue of the journal Sleep, found that chronically sleep-deprived individuals reported feeling “only slightly sleepy” even when their performance was at its worst during standard psychological testing. The results provide scientific insight into the daily challenges that confront military personnel, residents and on-call doctors and surgeons, shift workers, parents of young children, and others who routinely get fewer than six hours of sleep each night.