By Malika Ramani '21
Edited by Jessica Sevetson
According to the National Sleep Foundation, adults between the ages of 18 and 64 should sleep between 7 and 9 hours per night.  Yet almost all adults have experienced it: an insanely busy week when sleep is temporarily relegated to the back burner. Many of us then hit the snooze button once Saturday rolls around, convincing ourselves that we are taking care of our bodies by sleeping in to make up for several days of sleep deprivation. The results of a recent study, however, suggest quite the opposite – that sleeping in on weekends can actually have a detrimental effect upon health and disrupt our quality of sleep during the work week. 
The study, which followed 36 healthy young adults in a sleep laboratory over the course of nine days, was published this month in Curren t Biology. A team of investigators at The University of Colorado in Boulder closely monitored participants’ sleep, exposure to light, and food intake.  While one group of participants had the opportunity to sleep for nine hours each night, a second group was restricted to only five hours per night for the duration of the study. A third group of participants was restricted to only five hours of sleep from Monday to Friday, but the subjects were allowed to sleep in as long as they wanted on Saturday and Sunday before going back to the deprived schedule on Monday. 
Sleep deprivation has been studied extensively, and numerous studies have proven that adults who consistently get fewer than six hours of sleep experience impairments in mood, concentration levels, metabolism rates, and cardiovascular health. One group demonstrated that sleep-deprived adults had trouble completing even basic tasks, exhibiting five-fold increases in attention lapses and doubled reaction times in comparison to those who slept at least seven hours.  Furthermore, hormones that regulate hunger fluctuate due to chronic sleep deprivation. Leptin, which typically decreases appetite, drops, while ghrelin, which increases appetite, simultaneously increases.  People who are sleep deprived are much more likely to eat late-night snacks, leading to weight gain and an increased risk for diabetes and heart disease. In fact, both of the sleep-deprived groups in this recent study gained weight in just nine days due to snacking after dinner. 
Dr. Vsevolod Polotsky, the director of sleep research at Johns Hopkins, concludes that “weekend catch-up sleep is not protective,” articulating the fact that sleeping in cannot make up for the gains in weight and disruptions in circadian rhythms that come along with the extra hours.  Both sleep-deprived groups in the study showed declines in insulin sensitivity, and Polotsky attests that sleeping in only on weekends cannot correct this disrupted ability to regulate blood sugar, particularly if the weekend is followed by yet another week-long period characterized by insufficient sleep.
These findings are in contrast to previous research. One study published in December of 2018 in Journal of Sleep Research argued that many of the negative effects of sleep deprivation can indeed be corrected by sleeping in on weekends.  Tracking the self-reported sleep habits and death rates of 43,000 adults in Sweden over the course of 13 years, the study demonstrated that adults who slept fewer than 5 hours a night were 65% more likely to die early as compared to those who slept between 6 and 7 hours per night. The adults who reported short sleep during the week and longer sleep on weekends, however, were fully protected from this increased risk in mortality.  Lead study author Torbjörn Åkerstedt, a professor of psychology at The Karolinska Institutet, concluded that “weekday short sleep may be forgiven by weekend compensation”. 
Still, mortality risk is just one aspect of health. Some investigators argue that there are more immediate consequences of sleep deprivation for which weekends cannot compensate. Andrew Varga, an assistant professor and physician of pulmonary critical care and sleep medicine at Mount Sinai, cites evidence that individuals with disrupted circadian rhythms suffer higher risks of diabetes and heart disease. He also points out that memory and concentration can be affected by only two or three days of short sleep. 
These detrimental effects on memory and concentration exemplify why these sleep studies are directly relevant to high school and college students. A whopping 80% of teenagers sleep fewer than the recommended amount of nine hours per night, particularly during the busy school week.  In attempts to make up for this accumulated sleep deficit, many teens sleep longer on weekends, which unfortunately can lead to long-term consequences. Sleep researchers describe this phenomenon in terms of an “internal” and “external” clock: teenagers who delay their bedtime and wake-up times on weekends suffer from the equivalent of jet lag once Monday morning comes around, making it harder for them to concentrate or absorb information at the beginning of the school week (often known as the “Blue Monday effect”). 
In addition to maintaining relatively consistent bedtimes and wake-up times, researchers also recommend being active in the first two hours after waking up and avoiding naps throughout the day in order to improve overall quality of sleep.  Given that regular sleep is a crucial component of one’s overall wellbeing, the results of this study reinforce the significance of prioritizing the creation of a consistent sleep routine.
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