Social jetlag is the name given to the condition in which sleep patterns vary widely between workdays and weekends or holidays, with sleep deprivation on weekdays being compensated for by a lie-in on weekends. This may severely confuse and disrupt the natural circadian rhythms of the body, with harmful metabolic effects. Such effects include obesity and diabetes, which are more common in such individuals.
A causal relationship has yet to be proved between this type of health disorder and metabolic disorders, because reverse causation may also be possible. More and more evidence is coming in, on the other hand, of a relationship between sleep deprivation or irregular sleep rhythms, and academic performance.
Do teenagers need less sleep?
Almost 90 percent of high school students in the US are unable to get adequate sleep at night, and the number of hours spent in sleep is decreasing from a required 8-10 hours to less than 4-5 hours. This may be caused by intense academic pressure, an increasing number of assignments which are required to meet higher standards, and a disproportionate amount of time spent with electronic communication or music gadgets, partly in order to relieve the stress of student life.
Such shortening of the hours of sleep causes a host of unwanted consequences, such as poor concentration, microsleeps while driving with resulting increase in accidents, mood disorders, and low grades. Such problems occur across all lines of income, social status, and academic coursework.
However, the most serious sleep deprivation may occur among teenagers and young adults, whose circadian rhythm is being reset to allow them to stay up later by as much as two hours. Thus the typical bedtime for this group is around 11 pm. In contradiction to this biological tendency to get nine hours of sleep every night starting late at night, is the social need to get up early so as to attend school on time – generally by 7:30 am. This reduction in allowable sleep time means that teens are chronically sleepy and sleep-deprived, becoming unable to process mental or emotional data well. This is because of inadequate REM sleep, which is the type of restful sleep and is associated with permanent learning.
Social jetlag and the circadian rhythms
The changing of sleep patterns on the weekend, with late mornings and late nights out replacing the early morning rising on weekdays, upsets the master clock in the brain, leading to difficulty in reestablishing normal rhythms the next working day. There are several clocks around the body, which need to be coordinated in order for proper physiologic function.
This harmonious functioning requires that the circadian rhythms be maintained without substantial variation so that the master clock can set the other clocks correctly each day. Both the disruption of physiological rhythms and the lack of sleep potentiate each other to produce severe ill-health in adolescents.
Such ill-health may manifest as an inability to learn well, poor memory, and decreased ability to solve complex problems. Another area includes changes in or increased appetite, increased snacking on junk food, metabolic derangements, and weight gain or obesity. Adolescents with this pattern may also be at high risk for mood swings or disorders, disturbed or negative emotional states, and high-risk behavior, including poor judgment.
These factors are often already at risk during adolescence due to the numerous physiologic changes occurring at this time, and the combination of low sleep with disturbed biological rhythms can cause lethal long-term consequences.
Optimizing health and performance through sleep
For the reasons highlighted, a low-investment, low-risk, high-benefit intervention for adolescent health and well-being would be to recommend that parents enforce an earlier bedtime, before 11 pm, on weekdays, and only an hour or so extra on weekends. While a causal relationship is yet to be proved, students who sleep earlier and have more overall sleep on workdays, with less change on weekends, average better academic grades than others.
Studies have shown that sleeping at odd times results in dysregulation of the expression of many human genes. Social jetlag is one factor responsible for such sleep disruptions, and thus this may be an important mechanism of action of health deterioration in such situations.
Social jetlag affects sleep worst in ‘night owls’ or people who naturally wake later in the morning and peak late in the evening. Society’s demands naturally leads to a shortening of their sleep throughout the workweek, which is compensated for on weekends by a lie-in. It is often recommended by specialists in the field that work and school timings be adapted to natural rhythms wherever possible to improve productivity and performance, as well as good health.
Reviewed by Afsaneh Khetrapal BSc (Hons)