A team of researchers set out to uncover the impact of âsocial jetlag,â defined as the difference between a personâs natural circadian rhythm and actual sleep schedule as dictated by their social obligations, such as having to go work in the morning.
They looked at data from the Adult Health and Behavior Project Phase 2 Study, focusing in on 447 adult participants between the ages of 30 and 54 who worked out of their homes during the day for at least 25 hours per week.
Each participant wore a special wristband that enabled the researchers to monitor their movements and sleep activity for the full day (24 hours) over the course of one week. Upon analyzing the results from the wristbands, the team discovered that the majority of participants (85%) had later mid-sleep (the halfway stage of their sleep cycle) on days when they werenât working, which is an indication that on these days they woke up later than on the days when they did work.
After the seven-day period, the findings revealed significant differences between the health of participants who woke up closer to the same time every day and those who didnât. The adults who had a bigger shift in their sleep schedulesâas in more social jetlag, or a bigger gap between wake up times on working days and non-working daysâwere also more likely to show signs of unhealthy cholesterol levels, a wider waist, greater body mass index (BMI), and more problems with insulin resistance, compared to people who didnât have a big gap in wake up times.
These types of metabolic changes have all been linked to the development of a wide range of other more serious health concerns, including obesity, heart disease, and diabetes.
Surprisingly, the link between social jetlag and metabolic health risk remained the same even after taking into account other measures, such as calorie intake and the physical activity levels.
According to the studyâs lead author, Patricia Wong, this is the first study to look at the effects of relatively normal sleep schedules on average, middle-aged, working adults. Most of the previous studies have looked at more drastic changes in sleep schedules, such as shift workers whose inherent circadian rhythm is more frequently disturbed because of unusual working hours.
However, based on these latest findings, even just minor disruptions in otherwise healthy adults with reasonably normal schedules can have a negative impact on health. To try and minimize the effects of social jetlag, Wong suggests that individuals try to focus more on how to âmake informed decisions about structuring their schedules.â
Although this study didnât show a direct cause-and-effect relationship and more research still needs to be done, you may want to think twice about sleeping in on the weekends and holidaysâyou may feel groggy in the moment, but your body will thank you in the long run.
Sources for Todayâs Article:
Wong, P.M., et al., âSocial Jetlag, Chronotype, and Cardiometabolic Risk,â Journal of Clinical Endocrinology & Metabolism, 2015; doi: 10.1210/jc.2015-2923; http://press.endocrine.org/doi/pdf/10.1210/jc.2015-2923.