Night Owls Are 70% More Likely to Need a Disability Pension, Study Suggests : ScienceAlert

It is 11 pm, and your brain has finally decided to cooperate. The task that felt impossible all afternoon suddenly seems manageable. You want to read, finish something, or follow an idea.

Then the morning alarm rings. That energy has vanished, but the working day is starting anyway.

For night owls, this clash can feel familiar. A Finnish study suggests their difficulties may extend beyond mornings: evening types were more likely to receive a disability pension years before the usual retirement age.

Researchers followed 5,679 adults for 12 years. Before adjusting for other factors, evening types had an approximately 70 percent higher rate of receiving a disability pension than morning types, accounting for when pensions were awarded.

The finding appeared in both men and women, and persisted after accounting for socioeconomic factors, including education and income.

But health emerged as an important part of the explanation.

“We think that the generally poorer health of evening chronotypes (compared to morning chronotypes) was the most likely explanation of the heightened risk found in our study,” first author Tapio Räihä, a life course health researcher at the University of Oulu, told ScienceAlert.

Being a night owl describes more than a habit of staying up for another episode. Our chronotype reflects when we naturally tend to feel alert and sleepy. Some people favor mornings, others evenings, and many fall somewhere in between.

This timing has a strong genetic component, although environmental influences also shape its expression.

The new research drew on the Northern Finland Birth Cohort 1966, a population study following people born in two northern Finnish provinces.

In 2012, participants aged 46 answered questions about morning tiredness, preferred working times, and whether they considered themselves morning or evening people.

The analysis included 2,597 men and 3,082 women who had not already retired or received a disability pension. Around 10 percent of men and 12 percent of women were classified as evening types.

Researchers linked their responses to national pension records through 2023.

In Finland, disability pensions are awarded when health problems substantially reduce long-term working ability despite treatment and rehabilitation. The study included partial and full pensions, whether temporary or permanent.

During follow-up, 384 participants received their first disability pension.

Among men, that happened to 8.3 percent of evening types, compared with 5 percent of morning types. Among women, the proportions were 12.1 percent and 7.2 percent.

Most evening types did not receive a disability pension during follow-up. Only 21 evening-type men received one, leaving considerable uncertainty around the size of their association.

At the start, evening types generally reported poorer health, more sleep difficulties, and lower physical activity than morning types.

When researchers accounted for self-rated health, body mass index, smoking, alcohol consumption, and physical activity, the association weakened and became statistically non-significant in both sexes.

Adjusting separately for working hours and schedules also weakened it. In the model including all measured factors, the estimated difference between evening and morning types was small and statistically non-significant.

That does not settle the explanation. The authors caution that some adjusted factors could be steps along a possible pathway from chronotype to work disability. Accounting for them might therefore remove part of the relationship under investigation.

“Our study was observational, so we cannot prove cause-and-effect relationship,” Räihä said.

One possibility is a mismatch between internal rhythms and external demands. Finnish working days commonly begin around 8 am, when evening types may not perform at their best.

More than 70 percent of evening types who reported their schedules nevertheless worked daytime jobs.

Asked what might help, Räihä suggested morning outdoor light, dimmer lighting before bed, and limiting screens late at night. Caffeine use and untreated health problems also deserve consideration when addressing sleep difficulties.

These suggestions were not tested in this study.

“If you can choose a job that allows flexibility in schedules, that could also help,” he said.

Arranging tasks around periods of greater alertness might be another option. Whether schedule changes reduce disability pension risk, however, remains unknown.

Health, sleep, and working conditions were measured only at the beginning and could have changed. Finland’s healthcare and pension system also limit generalization.

“Also, the study needs to be replicated in other societies before making broad generalizations,” Räihä said.

Räihä said it is likely that evening types who maintain healthy habits and look after their sleep should not need to worry about their potential disability pension risk.  

The findings raise questions about how health and working schedules interact with natural rhythms. They do not predict how an individual night owl’s career will end.

The research has been published in Occupational & Environmental Medicine.