The tossing and turning at night, accompanied by a standard Monday through Friday workweek schedule, could leave many sleep-deprived and unable to get a full night’s sleep. According to the Global Sleep Survey, Americans get 30 to 40 minutes less of sleep on workdays, averaging about six-and-a-half hours of sleep on weeknights. While there is no “magic number” for sleep, the recommended number for healthy adults is seven to eight hours every night, according to the National Sleep Foundation. Many adults wait until the weekend to catch up on sleep, but can a person fully recover from the effects of workweek sleep loss?

According to a recent study, sleeping in on the weekends is not adequate enough to eliminate the cumulative effects that sleep debt from the workweek has on a person’s health. A team of researchers, led by Alexandros N. Vgontzas of the Penn State University College of Medicine, examined if “recovery” sleep, or sleeping more on the weekends, could reverse the adverse effects of workweek sleep debt in 30 healthy adults who were normal sleepers. The volunteers were placed on a 13-day schedule that involved spending nights in a lab. This sleep schedule mimicked a sleep-restricted workweek followed by a weekend with extra recovery sleep.

For the first four nights, the participants were allowed to sleep for eight hours to set a baseline for a healthy, normal amount of sleep. For the following six nights, the researchers woke the subjects two hours earlier — a total of six hours of sleep per weeknight. For the remaining consecutive nights, the subjects were allowed to sleep for a total of 10 hours. Brain waves were monitored by the researchers as the participants slept.

To examine the effect of sleep debt on health, the researchers used several different tests to monitor participants' interleukin-6 levels (a marker of inflammation) and cortisol (a hormone secreted during stress) at three different times throughout the study. These tests were done four days after getting eight hours of sleep, five days after getting six hours of sleep, and two days after getting 10 hours of sleep. Catheters were inserted into the participants’ arms as a means for the researchers to sample their blood every hour, according to Medical Xpress.

The test results revealed that restricted sleep increased inflammation. After two days of recovery sleep, the volunteers reported being less sleepy. Their interleukin-6 levels decreased, and their cortisol levels dropped significantly compared to baseline (at the beginning of the study). This suggests that the volunteers were already sleep-deprived before the start of the study.

To test cognitive function, the researchers asked the participants to take objective and subjective tests. The participants took an objective test, where researchers examined how quickly they were able to fall asleep when permitted to nap. As a subjective measure of sleepiness, the participants filled out questionnaires to assess how sleepy they felt. To test alertness, the subjects were asked to press a button whenever a dot appeared on the screen.

Overall, sleep recovery did not help attention performance. The participants' cognitive function did not improve after receiving recovery sleep during the weekend.

The findings suggest that there is no such thing as “catching up” on sleep on the weekends. Sleeping in does not erase all health issues associated with sleep debt. "Two nights of extended recovery sleep may not be sufficient to overcome behavioral alertness deficits resulting from mild sleep restriction," the authors of the study wrote.

"The long-term effects of a repeated sleep restriction/sleep recovery weekly cycle in human remains unknown."