Night owls reported more work-life strain and mental health symptoms in Finnish study

The study used data from 2,266 working participants in the population-based Healthy Finland Study. Participants had a mean age of 44, and 57% were women.

Researchers grouped people by circadian type, meaning their natural preference for being active and awake earlier or later in the day. They used a widely used single question from a morningness-eveningness questionnaire to identify morning, evening, and intermediate types.

The team asked about several parts of mental health. These included general mental health, anxiety symptoms, depression symptoms, suicidal thoughts, and whether participants had made healthcare visits. They used established questionnaires for general mental health, anxiety, and depression.

They also asked about work-life balance. In particular, they looked at whether work spilled into personal life and how well people felt they recovered from work. Recovery can mean winding down and regaining energy after the workday.

Evening types reported more work-life balance problems and more symptoms of mental disorders than other circadian types. The abstract does not provide the size of these differences, so it is not possible from the available information to say how large the increased symptom burden was.

The researchers also found that evening type was linked with health behaviors, including insufficient physical activity and risky alcohol use. However, the links between evening type, work-life problems, and poorer mental health remained after the analysis took account of these behaviors, as well as sex, age, and insufficient sleep.

Work spilling into personal life and poor recovery from work appeared to change the relationship between circadian type and mental health problems. These patterns were especially noted among people with a moderate circadian preference and those identified as definite evening types.

Poor recovery from work partly mediated the association between evening type and anxiety disorders. In everyday terms, that means difficulty recovering after work may account for part of the statistical link between an evening preference and anxiety problems. It does not mean recovery is the only explanation, or that improving recovery would necessarily prevent anxiety.

The study was population-based, which can help researchers examine patterns in a broad group rather than in one workplace. It also used validated questionnaires and adjusted for several factors that could be related to both daily routines and mental health.

Still, the findings show associations, not cause and effect. The abstract does not state how long participants were followed, and it does not establish which came first: work-life difficulties, poor recovery, or mental health symptoms. Other factors not included in the analysis could also contribute.

More research that tracks people over time would be needed to clarify whether changes in work schedules, workplace boundaries, or recovery opportunities affect mental health differently for morning and evening types. For now, the findings highlight that people’s natural daily timing may matter when researchers and employers consider work-life balance.