Sleep regularity matters for mental health

New research suggests that having a consistent sleep schedule may decrease the risks of depression and anxiety, regardless of the duration of sleep.

Analysis of data from the UK Biobank showed that compared with irregular sleepers, regular sleepers had a 38-percent lower risk of depression (hazard ratio [HR], 0.62, 95 percent confidence interval [CI], 0.52–0.73) and a 33-percent lower risk of anxiety (HR, 0.67, 95 percent CI, 0.58–0.77). [Psych Med 2025;55:e239]

Sleep regularity was measured using the sleep regularity index (SRI), with a score of 0 reflecting completely random patterns and a score of 100 indicating perfectly consistent sleep–wake patterns. Participants with the highest SRI scores were categorized as regular sleepers (≥71, 75th to 100th percentile), those with the lowest SRI scores were irregular sleepers (≤51, 25th percentile and below), and those with SRI scores between 52 and 70 were moderately irregular sleepers (25th to 75th percentile).

Moderately irregular sleepers also fared better than irregular sleepers, with a 20-percent reduced risk of depression (HR, 0.80, 95 percent CI, 0.71–0.90) and an 18-percent reduced risk of anxiety (HR, 0.82, 95 percent CI, 0.74–0.91).

A linear association was observed between sleep regularity and mental health outcomes, such that each standard deviation-increase in SRI score was associated with a 14-percent decreased risk of depression (95 percent CI, 0.82–0.90) and a 12-percent decreased risk of anxiety (95 percent CI, 0.85–0.92).

These findings highlight the importance of consistent sleep–wake patterns and suggest that even modest improvements in sleep regularity might yield mental health benefits, according to the investigators.

Independent risk factor

“The association between SRI and mental health outcomes persisted after adjusting for sleep duration, confirming that sleep regularity represents an independent risk factor beyond sleep quantity alone,” the investigators noted.

Even among participants meeting recommended sleep duration guidelines, irregular sleepers had significantly elevated risks of depression (HR, 1.48, 95 percent CI, 1.18–1.86) and anxiety (HR, 1.35, 95 percent CI, 1.11–1.64).

The highest risks were observed among participants who were both sleeping irregularly and nonrecommended sleep duration (depression: HR, 1.91, 95 percent CI, 1.55–2.35; anxiety: HR, 1.61, 95 percent CI, 1.35–1.93).

“This indicates that maintaining regular sleep–wake cycles may be equally or potentially more important than achieving the recommended sleep duration,” they said.

Consistent sleep schedule

The present study aligns with and expand upon recent investigations into sleep regularity as an emerging trend, according to the investigators. [Lancet Psychiatry 2018;5:507-514; Elife 2023;doi:10.7554/eLife.88359; Diabetes Care 2024;47:2139-2145]

Biological mechanisms such as circadian rhythm disruption, hypothalamic-pituitary-adrenal axis dysfunction, brain function impairment, and systemic inflammation may explain how sleep regularity can influence mental health outcomes.

Describing the implications of their findings, the investigators emphasized that public health campaigns and guidelines, which often focus on getting a certain number of hours of sleep, should be expanded to include the importance of maintaining a consistent sleep schedule.

From a clinical perspective, physicians should start asking patients about their sleep regularity, especially those who are at risk of or have depression and anxiety, the investigators said.

Simple interventions such as encouraging patients to go to bed and wake up at the same time each day could help in the prevention and management of mental health issues, they added.

The analysis included 79,666 participants from the UK Biobank (mean age 61.53 years, 54.75 percent female, mean BMI 26.62 kg/m²). Seven-day accelerometer data were used to calculate SRI scores and average sleep duration. The mean sleep duration in the overall population was 7.22 hr.

Of the participants, 20 percent were irregular sleepers, 60 percent were moderately irregular sleepers, and 20 percent were regular sleepers. Compared with irregular sleepers, regular sleepers were younger, had a lower BMI, were less likely to smoke and drink, and more likely to engage in moderate to high levels of physical activity and follow a healthy dietary pattern.

Over a median follow-up of 7.5 years, depression occurred in 1,646 participants, while anxiety occurred in 2,097.