Irregular sleep patterns are linked to a higher chance of mood swings and depression, according to a new study from Michigan Medicine.
The researchers found that over the long term, variation in sleep and wake cycles increase the risk of depression just as much as sleep deprivation or staying up late most nights.
The experts report that even in short term, people who have an irregular sleep schedule from day to day can experience just as bad of a mood as those who stayed up extra late the night before.
The study was focused on data from direct measurements of the sleep and mood of more than 2,100 first-year medical residents over the course of one year.
The interns all experienced long, intense work days with work schedules that changed from day to day. These irregular schedules altered their ability to have regular sleep patterns.
The study participants wore activity trackers, self-reported on their daily mood on a smartphone app, and were assessed using quarterly tests for depressive symptoms.
The study revealed that individuals with variable sleep schedules were more likely to score higher on standardized depression symptom questionnaires and to have lower daily mood ratings.
“The advanced wearable technology allows us to study the behavioral and physiological factors of mental health, including sleep, at a much larger scale and more accurately than before, opening up an exciting field for us to explore,” said study lead author Dr. Yu Fang, a research specialist at the Michigan Neuroscience Institute.
“Our findings aim not only to guide self-management on sleep habits but also to inform institutional scheduling structures.”
Dr. Cathy Goldstein pointed out that wearable devices that estimate sleep are now being used by millions of people, including the Fitbit devices used in the study.
“These devices, for the first time, allow us to record sleep over extensive time periods without effort on behalf of the user,” said Dr. Goldstein. “We still have questions surrounding the accuracy of the sleep predictions consumer trackers make, though initial work suggests similar performance to clinical and research grade actigraphy devices which are cleared by the FDA.”
According to Dr. Srijan Sen, the new findings build on what his team’s work has already shown about high risk of depression among new physicians, and other underlying factors that as associated with a heightened risk.
“These findings highlight sleep consistency as an underappreciated factor to target in depression and wellness. The work also underscores the potential of wearable devices in understanding important constructs relevant to health that we previously could not study at scale.”
The study is published in the journal npj Digital Medicine.