Nocturnal “owls” may be twice as likely as morning “owls” not to perform better at work and increase the risk of early retirement due to disability, finds research published online in the journal Occupational and environmental medicine.
Given the move to extend working life and delay the right to a pension, it might be worth considering a man’s chronotype, the researchers suggest.
Morning chronotypes, or ‘likes’ tend to grow better early in the morning, while evening chronotypes or ‘owls’ have a better effect in the evening. The chronotype is mostly genetic, but environmental factors, such as exposure to daylight, work schedules, and family life can also affect it.
Owls usually do not fall asleep early enough to recommend 7+ hours of sleep on normal weekdays, leading to sleep and sleep recovery on non-working days, known as social jet lag.
This mismatch is linked to health problems, while long-term lack of sleep is linked to poorer overall health and cognitive performance, potentially hampering productivity at work, researchers say.
To further investigate this and discover whether the chronotype could also be associated with early retirement for health reasons, the researchers relied on data from a 1966 study of the gender cohort of Northern Finland (NFBC1966).
This is a continuous general survey based on the population, which originally consisted of 12,058 children (6,169 boys and 5,889 girls), born in northern Finland in 1966.
When study participants were 46 years old, they were asked about their working life and health and were asked about their sleep patterns to find out their natural chronotype.
Participants rated their own performance at work on a scale of 0-10, using a proven scoring system (Work Ability Score). Their data were linked to national social security and pension registries.
The final analysis included about 2672 men and 3159 women, all of whom worked in 2012 and for whom all details were available. In the next 4 years, they were monitored in order to determine who stopped working and received a disability pension.
In that period, 84 people received a new disability pension; 17 people died, 3 of whom had a disability pension.
The proportion of those who were stingy, middle chronotype, and owl was: 46%, 44%, and 10% among males, and 44%, 44%, and 12% among females.
Compared to larks, owls had poorer scores for each variable related to sleep and health. Owls were more likely to report short sleep duration, insomnia, and high levels of social lag. They were also more likely to be unmarried and out of work.
Approximately 1 in 4 men (28%) and women (24%) classified as owls had poorer results at work when they were 46 years old, a significantly higher proportion than among likes or middle chronotypes.
The chances of poor performance were twice as high among owls as they were among stallions of both sexes, even after considering potentially influential factors such as sleep duration and working hours.
During the four-year follow-up period, poorer results were strongly associated with an increased risk of receiving a disability pension for both sexes, with male owls being three times more likely to receive a disability pension than male likes, although the influence of chronotype weakened significantly when taken in consider sleep patterns and working hours.
This is an observational study and as such cannot determine the cause. And the number of disability pensions taken during the follow-up period was small. Nor was it possible to measure the impact of an earlier life chronotype on later life disability, the researchers warn.
However, the findings are in line with the findings of previously published research, they point out.
“We suggest that the chronotype be taken into account when supporting [work performance], both in the promotion of health at the individual level and in the planning of work schedules at the organizational level “, the researchers conclude.
And it is especially important for owls to adopt a healthy lifestyle, get enough work time and work time that suits their chronotype, they add.
External review? Yes
Type of evidence: Observation
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