'Desynchronized rhythms': Michigan researchers reveal the best time to sleep

A new study conducted by the University of Michigan recently discovered the significant connection between sleep patterns and mood disorders.

According to University of Michigan News, the initiative — led by Daniel Forger, a professor in the Department of Mathematics and director of the Michigan Center for Applied and Interdisciplinary Mathematics — found that "when people’s sleep cycles are misaligned with their internal clocks, or circadian rhythms, it can have drastic effects on their moods."

Forger noted "that means getting sleep when the body’s expecting it provides a potent boost to one’s emotional state and could alleviate symptoms associated with mood disorders."

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The Intern Health Study — a project "funded by the National Institutes of Health at the University of Michigan which works with hundreds of first-year training physicians" — had "the interns complete routine mood surveys while wearing fitness trackers—namely, Fitbits—that monitor their heart rate, activity and sleeping habits."

University of Michigan reports:

Forger and his team have developed algorithms to assess Fitbit data and extract quantitative information about people’s circadian rhythms, their sleep cycles and how well those align. By coupling that with the Intern Health Study’s daily mood surveys and also using quarterly depression screening questionnaires, the team could establish links between those alignments and real-world measures of mental health.

The information from the questionnaire—the nine-item Patient Health Questionnaire, or PHQ-9, which is widely used in research and clinics—yielded a particularly striking figure when it came to people with desynchronized rhythms.

"Sleep is important to us, but maybe not in the same way we care about depression," Forger said. "But there’s been a tremendous amount of research coming out showing that mood affects circadian rhythms and sleep, and that circadian rhythms and sleep affect mood.”

Minki Lee, a lead author on the study, noted, "It’s not just, 'If you go to bed earlier, you will be happier. To some degree, that will be true, but it will be because your sleep schedule is aligning with your internal rhythms.'”

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Emphasizing that their study "is not going to solve depression," Forger added, "We need to be very, very clear about that."

He said, "But this is a key factor that we can actually control. We can’t control someone’s life events. We can’t control their relationships or their genetics. But what we can do is very carefully look at their individual sleep patterns and circadian rhythms to really see how that’s affecting their mood."

University of Michigan's full report is available here.