October 9, 2013
Sleeping In On Weekends Doesn’t Help You Fully Recover From Work Week
Lee Rannals for redOrbit.com - Your Universe Online
Researchers placed 30 healthy adult volunteers who were normal sleepers on a sleep schedule that mimicked a sleep-restricted workweek followed by a weekend with extra recovery sleep. Throughout the schedule, researchers assessed the volunteers' health and performance using a variety of different tests.
The volunteer sleepers were placed on a 13-day schedule that involved spending nights in a sleep lab. For the first four nights, the subjects were allowed to sleep for eight hours, setting a baseline for a healthy, normal amount of sleep. During the next six nights, the team woke the subjects up two hours earlier. For the following three nights, the subjects were allowed to sleep for 10 hours.
Researchers monitored the volunteers' brain waves during these sleep sessions. At three points during the 13-day schedule, the participants spent whole days at the lab taking part in various tests. Subjects had catheters inserted into their arms, and the researchers sampled blood every hour.
The scientists found that after five days of restricted sleep, the volunteers were significantly sleepier on both objective and subjective tests compared to baseline levels.
The team discovered that volunteers’ sleepiness increased significantly after sleep restriction, but returned to baseline after some recovery sleep. Even the levels of a molecule in blood that is a marker for the amount of inflammation present in the body returned back to normal after the weekend sleep. However, the participants' measures on a performance test that assessed their ability to pay attention deteriorated significantly through sleep restriction, and did not improve after recovery.
The scientists determined that although some stress relief can be found after a weekend of sleeping in, not all the negative effects created by sleep deprivation can be reversed after hitting the snooze button a few times on a Saturday.
"Two nights of extended recovery sleep may not be sufficient to overcome behavioral alertness deficits resulting from mild sleep restriction," the authors wrote. "This may have important implications for people with safety-critical professions, such as health-care workers, as well as transportation system employees (drivers, pilots, etc.)."
They said that even though the results provide some insight into the health side effects of a single week of sleep loss and recovery, reliving the cycle over and over again may have even more significant health effects.
"The long-term effects of a repeated sleep restriction/sleep recovery weekly cycle in human remains unknown," the authors said.