According to “The cumulative cost of additional wakefulness: dose-response effects on neurobehavioral functions and sleep physiology from chronic sleep restriction and total sleep deprivation,” getting only 6 hours of sleep is as bad as getting no sleep at all. Wait! Say what?!
That’s right. This sleep deprivation study, which was published in the journal Sleep, took 48 adults and restricted their sleep to a maximum of four, six, or eight hours a night for two weeks. And there was one unlucky group was deprived of sleep for three days straight!
The results: Subjects who got six hours of sleep a night for two weeks straight functioned as poorly as those who were forced to stay awake for two days straight.
So you can stop wondering how much is enough: the subjects who were allowed to sleep eight hours per night had the highest performance – on average. Subjects who got only four hours a night did worse each day. The group who got six hours of sleep seemed to be holding their own, until around day 10 of the study.
In the final days of the experiment, the subjects who were restricted to a maximum of 6 hours of sleep per night showed cognitive performance that was as bad as the people who weren’t allowed to sleep at all! In fact, getting only 6 hours of sleep was as bad as not sleeping for two days straight. And rounding out the study results: The group who got only four hours of sleep each night performed just as poorly, but they hit their low sooner.
Surprisingly, the 6-hour group didn’t think their sleepiness was all that bad, even as their cognitive performance was going downhill. So don’t fool yourself into thinking that 6 hours is enough. Get to bed!