Social jetlag leads to overweight

Less and less sleep: Social jetlag threatens overweight

12/05/2012

Not only long-distance travel over several time zones can trigger a jet lag. Those who work constantly due to shift work at different times or have an irregular leisure time behavior, also suffers from the consequences of disorders of the internal clock. According to a study, up to 70 percent of people in the western industrialized nations should „social jetlag“ to be affected. Researchers warn against the incalculable consequences for health.

Working life causes jetlag
Anyone who has already taken a plane trip from Germany to the United States will have felt the effects of a jet lag. Sleep disorders, fatigue, headaches and even migraines can clearly be noticeable symptoms here. However, according to a new scientific study, people suffer from jet lag not only after long air travel over numerous time zones. Different working or school hours as well as irregular leisure activities can also confuse the organism and thus the clock of the internal clock. In any case, scientists from the University of Munich report to study director chronobiologist Till Roenneberg. According to the research team, as many as two-thirds of people in western industrialized countries are affected by the health consequences that accompany them.

In the trade magazine „Current Biology“ The researchers report a long-term study that lasted over ten years. For this purpose, about 65,000 subjects completed a questionnaire online at intervals. The subsequent data analysis has shown that a life against the internal clock increases the risk of overweight and obesity. Threatened by the acquired overweight „severe sequelae such as metabolic disorders such as diabetes“. I also have „Obesity reaches a level of crisis in industrialized societies.“

In obesity tendency to obesity
A closer look at the data showed, however, that the context turned out to be a correlation. Only study participants who already exceeded the body mass index (BMI) of 25, showed an increase in weight during the course. From a value of 25, people who are not over-trained speak of being overweight. On the other hand, whoever had a BMI value below 25 did not show any significant increase in weight. In addition, it could be seen that the effect only occurred when the jet lag exceeded a time limit of two hours. At a „small jet lag“ of less than an hour, the researchers statistically calculated even a decrease in body weight.

Among scientists remains undisputed that sleep disorders or „bad sleep“ endangers the health. Essentially, it is not just about the duration of sleep, but also about the time of sleep. Doctors suspect that the sleep behavior is also genetically determined. So there are different ones „chronotypes“, who divide into late risers or early risers. Sleep researchers also speak of in this context „owls“ or „larks“. In addition, the sleep requirement of humans differs. Some people need more and others less sleep. Who gets up late and to the „owls“ heard, can not do anything for his socially less accepted disposition. However, those are also more susceptible to one „social jetlag“.

Based on data collection, around 70 percent of people in Western countries are affected by a chronic jet lag that lasts at least one hour. About 35 percent even showed a two-hour or more jet lag. In addition, the researchers observed a continuous decline in sleep duration in the last decade. The strongest persons are under the age of 20 affected. They are overly common among the „owls“, but they usually have to go to school on weekdays.

How much sleep this lacks can be recognized on the basis of the school-free days. On a Sunday, teenagers sleep on average three hours more than in school week. Only in the case of young children and seniors do the stay and bed times in the week and on weekends remain above average.

Less and less time to sleep
„The decrease in sleep duration is becoming more pronounced on weekdays during the last decade“, the authors write in the study report. This is questionable, because it also increases the social jet lag occurs. In the weeks, the sleep duration decreases continuously, while more and more people tend to the „chronotypes“ (Owls) tend. In addition, humans are exposed to more than natural, artificial light. The weak light in homes and offices is compared to sunlight „not adequate clock“. Thus, in addition, the „inner clock“.

„Our results show that life against the clock can be a factor in the epidemic of obesity“, the researchers write in their summary. The observations should also play a role in the discussion on the implementation of summer time, because the time change contributes to the social jet lag. „Our data suggest that improving correspondence between biological and social clocks may contribute to the treatment of obesity.“ (Sb)

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Picture: Berwis