The Grapevine

Social Jetlag: Mismatch Between Circadian Rhythm And Actual Sleep Schedule Can Lead To Metabolic Problems

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Sleeping more on the weekends than you do on weekdays can create an imbalance in your circadian rhythm. Pixabay, public domain

Sleep is essential to your health and wellbeing; that’s been proven time and again. Sleep deprivation has been linked to a variety of disorders, including high blood pressure and heart problems. But even if you’re not sleep deprived, an imbalance in your sleep schedule can impact the risk of developing diabetes, heart disease, or metabolic syndrome, according to a new study published in the Journal of Clinical Endocrinology & Metabolism.

"Social jetlag" is the mismatch between your body's natural circadian rhythm, and your socially-imposed sleep schedule. For instance, while your body may be prepared to go to sleep at midnight every night, your social schedule might require you to go to sleep much later after going out with friends — or even earlier, if you share a bed with a partner. While these little imbalances in schedule and circadian rhythm may seem minor, they may contribute to metabolic changes in the body, the researchers found.

“Other researchers have found that social jetlag relates to obesity and some indicators of cardiovascular function," said Patricia Wong, of the University of Pittsburgh and an author of the study, in the press release. "However, this is the first study to extend upon that work and show that even among healthy, working adults who experience a less extreme range of mismatches in their sleep schedule, social jetlag can contribute to metabolic problems. These metabolic changes can contribute to the development of obesity, diabetes, and cardiovascular disease.”

For the study, the researchers analyzed 447 men and women who had taken part in the Adult Health and Behavior Project Phase 2 study. The participants were middle-aged adults (30 to 54 years old), and they worked at least 25 hours per week. They wore a wristband that measured their movement and sleep for 24 hours a day throughout the duration of the study.

Participants slept less on workdays than they did on the weekends or free days, the researchers found. In fact, 85 percent of them had a later midsleep point (the halfway point in their sleep cycle) on free days compared to work days. Those who had the biggest mismatch between their midsleep point on work days and free days ended up having poorer health profiles — worse cholesterol, higher fasting insulin levels, larger waist circumferences, and higher body mass indexes (BMI). In short, sleeping more and later on weekends, but not matching up with those times on the weekdays, can lead to health problems over time.

Social jetlag can influence other aspects of our health, including diet and eating times. A 2012 study on social jetlag found irregular sleep and eating schedules were linked to a higher BMI, obesity, and digestion problems. Another recent study found losing 30 minutes of sleep every day could impair metabolic function.

“If future studies replicate what we found here, then we may need to consider as a society how modern work and social obligations are affecting our sleep and health,” Wong said. “There could be benefits to clinical interventions focused on circadian disturbances, workplace education to help employees and their families make informed decisions about structuring their schedules, and policies to encourage employers to consider these issues.”

Source: Wong P, Hasler B, Kamarck T, Muldoon M, Manuck S. Social Jetlag, Chronotype, and Cardiometabolic Risk. The Journal of Clinical Endocrinology & Metabolism. 2015.

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