A study published in npj Digital Medicine showed that irregular sleep schedules can affect mood and increase the person's risk of developing depression symptoms.
The study collected data from direct measurements of the sleep and mood of more than 2,100 first-year residency physicians (interns) over a one year period. The data was gathered by tracking the interns' sleep and other activities 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.
The interns all experienced the long intense work days and irregular work schedules that are the hallmark of this time in medical training. These factors, changing from day to day, altered their ability to have regular sleep schedules.
The research revealed that 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 researchers note that these findings only reinforce what's already known about the association between sleep, daily mood and long-term risk of depression.
"These findings highlight sleep consistency as an underappreciated factor to target in depression and wellness," says Srijan Sen, MD, PhD, coauthor of the study.
The team did point out that the young group of people in the study (an average age of 27) are not representative of the broader population. The researchers hope that more studies will examine other populations using similar devices and approaches, to see if these findings about sleep hold up there, for instance, in parents of young children, where sleep is regularly interrupted.
