Evening types face a higher risk of receiving a disability pension

People with an evening chronotype were found to have a 1.7-fold higher risk of receiving a disability pension compared with morning types, according to a study led by the University of Oulu. The most likely explanation is that evening types tend to have poorer health and face more difficulties in working life than morning types.

“Poorer health among evening types may stem from less healthy lifestyles, such as smoking and low levels of physical activity, as well as disruption of the body's internal biological clock, which can lead to sleep problems. They are also at higher risk of a range of mental and physical illnesses,” says researcher Tapio Räihä.

The study drew on data from the Northern Finland Birth Cohort 1966. The baseline sample included 5,679 participants, of whom 2,597 were men and 3,082 women. The participants were followed for 12 years.

To determine chronotype, participants answered questions at age 46 concerning, among other things, how easy it was for them to wake up in the morning, how tired they felt during the first half-hour after waking, their preferred time of day for working, and whether they considered themselves a morning or evening person. These data were linked with national registers containing information on employment histories and pensions.

A total of 253 men (9.7%) and 381 women (12.4%) were classified as evening types, while 1,182 men (46%) and 1,355 women (44%) were classified as morning types. The remaining participants were classified as intermediate types.

During the follow-up period, disability pension was granted to 135 men (5.2%) and 249 women (8.1%).

Evening types were more likely than morning types to end up on disability pension. Among evening-type men, 8.3% received a disability pension decision during the 12-year follow-up, compared with 5.0% of morning-type men. Among women, the corresponding figures were 12.1% and 7.2%.

The clear majority of participants remained in working life: 89.3% of evening-type men and 86.6% of evening-type women were still part of work forcethroughout the study period.

Social jetlag increases the risk of health problems

People classified as evening types had approximately a 70% higher risk of receiving a disability pension than morning types. The association was observed among both men and women and remained unchanged even after accounting for socioeconomic factors such as educational level and occupational group.

The evening types in this study were, on average, more highly educated than morning types, and a higher socioeconomic status would normally be expected to reduce the risk of disability pension. However, the health of evening types may already have deteriorated by the ages of 50 to 60 to the extent that their work ability has declined and their risk of disability pension increased.

People can be grouped into chronotypes according to the sleep-wake pattern that comes most naturally to them. Based on the timing of bodily functions and alertness, individuals can be classified as morning, intermediate, or evening types. This study also demonstrated a link between questionnaire-based chronotype and genetic chronotype profiles.

“Because evening types find it difficult to fall asleep early, they tend to accumulate more sleep debt during work and school weeks than others. They compensate by sleeping longer on days off. The difference between sleep schedules on workdays and free days, known as social jetlag, is more pronounced among evening types than morning types. Together with the disturbance of the innate circadian rhythm, social jetlag increases the risk of health problems over the long term,” Räihä explains.

However, a clear association between chronotype and disability pension has not previously been demonstrated.

A large proportion of the population are evening types

According to the researchers involved in the study, poorer health among evening types is the most likely explanation for their relatively higher rates of disability pension. Disability pension was defined broadly to include full disability pension, partial disability pension, temporary rehabilitation allowance, and partial rehabilitation allowance.

In Finland, disability pension is granted only after a serious and long-term decline in health. Evening types make up a substantial share of the population, and their health and ability to remain in the workforce until retirement age pose an important challenge for a sustainable economy, the researchers note.

Because this was an observational study, no firm conclusions can be drawn about cause-and-effect relationships. In addition, participants’ health and life circumstances may have changed after the baseline assessment, and such changes could not be taken into account.

The study was published in Occupational & Environmental Medicine: Evening chronotype and disability pensions: 12-year register-based follow up of middle-aged adults from the Northern Finland Birth Cohort 1966
DOI: 10.1136/oemed-2026-110995

Räihä T, Merikanto I, Nerg I, Korhonen M, Kantojärvi K, Ala-Mursula L, Heikkala E. Evening chronotype and disability pensions: 12-year register-based follow-up of middle-aged adults from the Northern Finland Birth Cohort 1966. Occup Environ Med. 2026 Sep 29:oemed-2026-110995. doi: 10.1136/oemed-2026-110995. Epub ahead of print. PMID: 42810963.

The research was funded by the North Ostrobothnia Regional Fund of the Finnish Cultural Foundation, the European Research Council (ERC), and the European Union’s Horizon Europe programme.