The participants spent seven days in the sleep laboratory. For the first two nights, everyone spent 10 hours in bed. For the following five nights, participants only spent four hours in bed per night. During waking hours, the lights were kept on, and they were allowed to play games, read, and watch movies. They were not allowed to consume foods and drinks that could affect their sleep, such as caffeine, turkey, bananas, or alcohol.
Despite the inconsistent sleep patterns throughout the seven-day trial, results for the memory and cognitive skills were similar in both groups.
Dr. Mark Mahowald, medical director of the Minnesota Regional Sleep Disorders Center, said that the study results are important because people tend to make sweeping statements about sleep deprivation -- when sleep is different for everyone because there are huge genetic components that contribute to our slumber.
"The medical profession has been guilty for decades of sleep deprivation in its trainees, so they made recommendations of the number of hours someone should work, but they made across-the-board, sweeping recommendations," said Mahowald. "The implication is that everyone is sleep-deprived and sleep-deprivation does the same thing to everyone, but the tolerance and range of sleep is so different for different people."
"A one-size-fits-all policy is probably not a very wise idea when it comes to sleep," said Mahowald. "Our society has equated sleepiness with defects of character, like laziness and depression, but really, some people are generally sleepier during the day. They're more prone to naps, and to sleeping in. We have to accept the fact that sleep duration is genetically determined and not a sign of defect."
So what's a tired person to do? Not much, said doctors, but Dr. Goel said she hopes to continue her research with genetic biomarkers. She said they might help to predict a person's response to sleep deprivation, especially for those who work a night shift, travel often through many time zones, or those who lose sleep due to personal or family obligations. At any rate, doctors said that tiredness is certainly a manageable condition.
"Down the line, if someone is carrying this gene, maybe they can employ a countermeasure," said Goel. "Maybe they could have caffeine to counteract some of these symptoms."