A recent Finnish study has found that individuals who identify as night owls face a significantly higher risk of early disability retirement compared to those with morning chronotypes. Researchers from Oulu University analyzed data from a long-term population study to examine the relationship between natural sleep-wake preferences, or chronotypes, and the likelihood of receiving disability benefits.

Chronotypes categorize people based on their preferred timing for sleep and activity: morning types, evening types, and intermediate types. While prior research has linked evening preferences with poorer health outcomes and occupational difficulties, this study is among the first to measure the impact on disability pension claims over an extended period.

The study included 5,679 participants aged 46 from northern Finland, who were assessed through surveys about their sleep habits, alertness in the morning, preferred working times, and self-identification as either morning or evening types. The sample consisted of 9.7% men and 12.4% women classified as evening types, while 46% of men and 44% of women were morning types. The remaining participants fell somewhere in between.

Over a follow-up period of 12 years, 135 men and 249 women in the cohort were granted disability pensions, which in Finland are awarded only after severe and prolonged health decline. After controlling for socioeconomic variables such as education and occupation, researchers found that evening types had a 70% greater risk of obtaining disability pensions than morning types.

The authors suggest that the heightened vulnerability of evening chronotypes may stem from lifestyle factors and the misalignment between their internal biological clocks and societal norms, leading to what is often called social jetlag. This desynchronization can result in chronic sleep problems, which may contribute to deteriorating health and reduced work ability over time.

Despite the biological predisposition of evening types to later activity schedules, the study found that over 70% of these individuals worked conventional daytime hours. This mismatch between preferred and required schedules could pose challenges to maintaining long-term health and work productivity.

The researchers emphasize that evening chronotypes account for a substantial portion of the population, and their increased risk of early disability raises concerns for workforce sustainability and economic impact. They advocate for greater awareness of chronotype-related health risks and consideration of more flexible working arrangements to better accommodate natural sleep patterns.