For the new study, the researchers used data from a major Finnish population database to explore whether chronotype was linked to health-related early retirement. The data included just over 12,000 children born in 1966 in northern Finland. At age 46, the same participants were asked about their working life and health, including sleep patterns and work performance. Their data were linked to national registries for social security and pension payments.
Of that group, the investigators analyzed nearly 2,700 men and about 3,200 women who were all still working in 2012, monitoring for four years to see who had stopped working and taken a disability pension. During this period, 84 people received a new disability pension. In all, 17 people died, including three of those who had taken a disability pension.
About 46% of men and 44% of women were early birds, another 44% of men and women were an intermediate chronotype, and 10% of men and 12% of women were night owls.
Compared with early birds, the night owls had worse ratings for all variables related to sleep and health, including short sleep duration, insomnia, and high levels of social jetlag. They were also more likely to be unmarried and out of work, the findings showed.
About 28% of men and 24% of women who were night owls reported underperforming at work at age 46, significantly higher than early birds and the intermediate chronotype, the study authors noted.
During the four-year monitoring period, underperformance was strongly linked to a heightened risk of taking a disability pension for both genders. The impact of chronotype was significantly weakened when sleep patterns and working times were taken into account, the researchers said in a journal news release.
As this was an observational study, the authors pointed out that they could not establish a cause-and-effect relationship.
More information
The American Psychological Association has more on the importance of sleep.
