Irregular sleep linked to worse anxiety and depression

By Stephen Beech

Not getting up and going to bed at the same time each day can damage mental health, suggests new research.

Irregular sleep-wake schedules may lead to more severe symptoms of anxiety, depression and even loneliness by disrupting the body’s natural clock, according to the American study.

While previous sleep research has largely focused on sleep duration and sleep quality, the new study examined “sleep regularity” — how consistently people followed the same sleep-wake patterns each day.

Researchers from the University of California analyzed months of data collected from wearable devices worn by more than 20,000 participants.

Study senior author Ashley Mason said: “Regular sleep and wake time help keep circadian rhythms aligned.

“Irregular sleep-wake timing may weaken circadian alignment, which is associated with depression and other mental health disorders.”

She says irregular sleep schedules can also disrupt the timing of light exposure, meals, exercise and social activity — all of which help regulate the circadian rhythm.

For the study, published in the journal Scientific Reports, researchers analyzed data from around 23,000 participants enrolled in TemPredict, a project launched in 2020 to investigate whether data from wearables could help identify COVID-19 before people recognized symptoms.

Participants, whose average age was 46, contributed an average of 154 days of sleep data, which allowed the research team to examine sleep regularity over time.

They also created a “typical week” snapshot to compare their findings with previous, much shorter studies on sleep regularity.

The researchers discovered that associations between sleep and mental health were stronger with the longer-term data.

Participants wore a smart ring that uses sensors to detect movement and measure vital signs.

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The smart ring used the data to estimate when they fell asleep and woke up.

Researchers were then able to calculate each participant’s Sleep Regularity Index (SRI), ranging from zero to 100, with higher scores indicating more consistent sleep patterns.

Participants’ depression, anxiety and loneliness were assessed by a monthly self-reported survey.

Overall, less regularly timed sleep correlated with greater depression and anxiety.

In the long-term analysis, participants with few symptoms of depression or none at all had an average SRI of 84, compared with 83 for those with mild depressive symptoms, 81 for moderate symptoms and 75 for severe symptoms.

Participants with normal levels of anxiety had an average SRI of 84, compared to 79 for those with severe anxiety.

Participants with elevated loneliness also had less regular sleep-wake schedules.

Study first author Severine Soltani said: “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.

“For someone with an SRI of 75, that shift in sleep schedule might be closer to an hour and a half.”

Mason said the association between poor sleep and poor mental health could be “codirectional” — irregular sleep could also be explained as a symptom of poor mental health.

She added: “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.”

The research team says future studies should test whether helping people establish more regular sleep schedules can improve mental health.