WebMD WebMD recommended seven to eight hours 7–9 hours per night 7–9 hours per night didn’t sleep enough enough sleep by 32% recommended 7 to 9 hours of sleep every night Sleep deprivation Sleep deprivation enough sleep at least seven to nine hours of sleep a night Sleep Sleep deprivation enough sleep recommended seven to eight hours WebMD enough sleep these effects Sleep deprivation nine hours of sleep Sleep deprivation enough sleep recommended seven to eight hours WebMD enough sleep recommended seven to eight hours recommended 7 to 9 hours of sleep every night Sleep