The link between insomnia and depression is well-established, but a new study shows that even an irregular sleeping pattern, with a normal number of hours of sleep, can affect mood and depression risk.
The study, conducted at the University of Michigan, looked at the sleep patterns of medical interns, first year doctors, who complete a year of work under supervision, a program that is notorious for intense work days and irregular schedules. The interns wore a commercial tracking device (Fitbit) and completed a daily mood check on a smartphone app. In quarterly tests for signs of depression, those whose wrist-worn devices showed the most irregular waking and sleeping schedules also had higher scores for depression risk. Study authors noted that those with irregular sleep patterns were even likely to wake up in a “foul mood” in the morning.
Michigan Medicine’s Intern Health Study, led by Srijan Sen, MD, PhD, has been studying the mood and depression risk of first year medical residents for more than a decade. “These findings highlight sleep consistency as an underappreciated factor to target in depression and wellness,” he said. Study authors were also excited about the potential of consumer-focused wearable devices like the Fitbit to give greater understanding of a variety of factors that would have been difficult to study on a large scale in the past. The study is preliminary and suggestive, and authors note that, with an average age of 27, the study participants are not representative of the wider population. Still, it gives new weight to factors that previously had not been considered, and offers new routes for future research.