Male ‘night owls’ face an increased risk of early retirement because of disability, a study has suggested.
According to a University of Finland study, which has been published in the journal Occupational & Environmental Medicine, people with an evening chronotype (E-types) are more likely to underperform at work and stop working due to disability than morning chronotypes.
A person’s chronotype – whether they perform better during the evening or morning, depending on their preferred sleep cycle – can be influenced by environmental and age-related factors, as well as their genetics.
The study looked at the chronotype of 2,672 men and 3,159 women and whether they claimed one of Finland’s disability pensions. The participants were aged 46 when they took part in a survey in 2012.
E-types represented 10% of men and 12% of women.
During a four-year follow-up period between 2013 and 2016, 84 people received a new disability pension. Three per cent of E-type men and 2.6% of E-type women claimed the pension.
Men who were “night owls” were three times more likely to claim the disability pension than men who were “morning larks”.
No significant association between the evening chronotype and disability pension provision was identified among women.
The researchers said that occupational health practitioners and employers should take a person’s chronotype into account in health promotion and planning of work activities.
“Especially with E-types, the importance of a healthy lifestyle, sleep and suitable working times should be remembered. Actions matching the internal and social rhythm, targeted to either the individual, the environment or both, could help to support careers of E-types,” the study said.
The researchers urged some caution over the findings. The paper said that the number of early disability pension cases was “expectedly small” during the four-year follow-up period.
It said: “It is possible that existing health problems in 2012 may have affected both the reporting of chronotype and the risk of subsequent pension. However, the adjustment for self-reported health in 2012 was targeted to capture this potential confounding.
“Moreover, there has been greater attrition in the study participants among men and among those with lower socioeconomic status, who generally have poorer health. In Finland, office workers typically start working rather early at 08:00 and manual workers start even earlier, which may influence the impact of late chronotype on work ability.
“Finally, unmeasured uncontrolled factors are always possible in an observational study like ours.”