An irregular sleep schedule can increase a person’s risk of depression over the long term as much as getting fewer hours of sleep overall, or staying up late most nights, a new study suggests.
The study, conducted by a team from Michigan Medicine, the University of Michigan’s academic medical center, uses data from direct measurements of the sleep and mood of more than 2,100 early-career physicians over one year. It’s published in npj Digital Medicine.
The new paper is based on data gathered by tracking the interns’ sleep and other activity through commercial devices worn on their wrists and asking them to report their daily mood on a smartphone app and take quarterly tests for signs of depression.
Those whose devices showed they had variable sleep schedules were more likely to score higher on standardized depression symptom questionnaires, and to have lower daily mood ratings. Those who regularly stayed up late, or got the fewest hours of sleep, also scored higher on depression symptoms and lower on daily mood.
The findings add to what’s already known about the association between sleep, daily mood and long-term risk of depression.
