While most adults are recommended to get seven to eight hours of sleep a night, the fact of the matter is that there are some of us who need more sleep than that, and some who are perfectly capable of functioning on less. Members of the latter group -- so-called “short sleepers” -- usually sleep less than six hours a night and are able to feel alert and refreshed the morning after, despite the little sleep.
Now, researchers from The Center for Applied Genomics at the Children's Hospital of Philadelphia have discovered a genetic variant that could help explain this "short sleep" phenomenon.
The findings, detailed in a new issue of the journal SLEEP, involved the study of 100 healthy pairs of twins. Researchers found that people who had a mutation of the BHLHE41 gene, called p.Tyr362His, only slept five hours a night, on average. Their twins who didn't have this gene mutation, on the other hand, slept six hours and five minutes each night.
People with the gene mutations also didn't seem to experience the detrimental effects of sleep deprivation as much as their mutation-lacking twins. After going 38 hours without sleep, they had 40 percent fewer performance lapses on cognitive tests, on average, compared with their twins without the gene mutation. They also required less recovery sleep after sleep deprivation -- sleeping eight hours after the period with no sleep -- compared with their twins, who needed nine-and-a-half hours of recovery sleep.
Of course, the amount of sleep a person needs isn't solely dependent on the sleep your body needs to function optimally (called the "basal sleep need"). Something called sleep debt -- sleep lost from awakenings, bad sleep habits and the like -- is also important to take into account when figuring out how much sleep your body needs.