Many people work late into the night during the workweek, thinking that their bodies would recover from lost sleep during the weekend, but according to a study on Science Daily, this isn’t necessarily true.

Researchers led by Alexandros N. Vgontzas of the Penn State University College of Medicine assigned 30 healthy adults a sleeping schedule. For the first four nights, the participants were allowed to sleep for eight hours. The next six nights saw them sleeping for only six hours, while the last three had them in bed for 10 hours.

During the study, the researchers analyzed the participants' brain waves and monitored their blood samples for the inflammation marker interleukin-6 and the stress hormone cortisol. They also tested the subjects’ sleepiness and attention levels.

The results revealed that after five days of irregular sleep, the participants showed an increase in interleukin-6 levels, although their cortisol levels showed little change. They also scored lower in tests of wakefulness and attentiveness. On the other hand, two days of "recovery sleep" revealed a decrease in interleukin-6. Cortisol levels also dropped, suggesting that the participants were already sleep deprived prior to the study. They were also less sleepy. However, their results in the tests did not improve.

This shows that lack of sleep may cause impaired concentration and reasoning. So instead of staying up late during weekdays and bunking up for 10 hours during weekends, it's best to have at least seven to eight hours of sleep on a daily basis.

(Photo by Timothy Krause via Flickr Creative Commons)