A new study has suggested that an irregular sleep pattern increases depression risk in the long term as much as staying up late at night or getting fewer sleep hours overall.

Irregular sleep schedules and staying awake late affects mood

The study indicated that individuals who have varying waking times tend to have a foul mood when it comes to mood the following day. This is the same as those up late into the night or got up very early in the morning. Michigan Medicine researchers at the University of Michigan academic medical center used data from direct sleep and mood measurement of over 2,100 early-career physicians in a year. The study was published in the npj Digital Medicine.

The interns, which are first years of residency training after medical school, experienced irregular work scheduled and intense workdays, which are the hallmark of medical training. The changing factors from day to day changed the ability of the interns to have regular sleep schedules. The study is based on data collected by tracking the interns’ activity and sleep through devices worn on wrists. Researchers also asked the interns to report on their daily mood on an app and take quarterly assessments for depression signs.

Researchers used wearable devices to monitor sleep patterns and mood

Interestingly, those whose devices indicated they had variable sleep patterns were likely to score higher on the standardized depression symptoms questionnaires. Equally, they had lower mood ratings per day. Also, interns that stayed up late or had few hours of sleep scored high on the depression symptoms with lower daily mood. These findings add to what is already known about the correlation between daily mood, sleep, and long-term depression risk.

Yu Fang, the study’s lead author, said that the use of advanced wearable technology enabled the researchers to study mental health’s physiological and behavioral factors accurately, including sleep and on a larger scale than in the past. Fang said the study findings will guide self-management on sleep habits and inform institutional scheduling structures.