FRIDAY, Nov. 13, 2026 (HealthDay News) — An erratic sleep schedule appears to negatively impact your mental health, a new study says.
People who don’t consistently fall asleep and wake up at the same time every day tend to have more severe symptoms of anxiety, depression and loneliness, researchers reported Nov. 12 in the journal Scientific Reports.
As little as an extra half-hour variation in your sleep schedule can impact your mood, researchers found.
Irregular sleep schedules can disrupt a person’s daily exposure to sunlight, the timing of their meals and exercise, as well as their social activity, researchers said. All these factors impact a person’s internal body clock, which is known as their circadian rhythm.
“Regular sleep and wake time help keep circadian rhythms aligned,” senior researcher Ashley Mason, director of the University of California San Francisco's Sleep, Eating, Affect Laboratory, said in a news release. “Irregular sleep-wake timing may weaken circadian alignment, which is associated with depression and other mental health disorders.”
For the new study, researchers analyzed data from about 23,000 people participating in a study initially launched to see whether wearables could help doctors identify COVID-19 before symptoms occurred.
The participants contributed an average of 154 days of sleep data, which allowed researchers to examine their sleep patterns over time.
The research team calculated a “typical week” snapshot of each person’s sleep, using a Sleep Regularity Index (SRI) that ranges from zero to 100. Higher scores indicate more consistent sleep patterns.
People in the study also filled out monthly surveys tracking their depression, anxiety and loneliness.
Results showed that irregular sleep is linked to worse mood problems:
People with severe symptoms of depression had an SRI of 75, compared with 81 for moderate symptoms, 83 for mild symptoms and 84 with few to no symptoms.
Those with severe anxiety had an SRI of 79, compared with 84 for those with normal levels of anxiety.
Folks feeling higher levels of loneliness had an SRI of 82, compared to 84 for those with less loneliness.
“Someone with an SRI of 84 might go to bed and wake up roughly an hour earlier or later than the previous day, on average,” lead researcher Severine Soltani, a former doctoral student at the University of California San Diego, said in a news release. “For someone with an SRI of 75, that shift in sleep schedule might be closer to an hour and a half.”
It’s possible that this link between poor sleep and worse mental health could work in both directions, Mason said. Sleep could be contributing to mood problems, but mood problems also can affect a person’s sleep.
“Other longitudinal research provides some reason to think that irregular sleep may come first and contribute to later poor health, rather than being solely a consequence of it,” Mason said.
Future research should test whether a more regular sleep schedule can improve the mental health of people, researchers concluded.
More information
Harvard Medical School has more on sleep and mood.
SOURCES: University of California San Francisco, news release, Nov. 12, 2026; Scientific Reports, Nov. 12, 2026
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