LONDON — Are you someone who stays up late into the night, or do you rise with the sun each morning? A new study finds that a person’s sleep preferences may actually reveal how well they do their job. Researchers in Finland say “night owls” are twice as likely to say they struggle to perform at work. Even more concerning, people who stay up late also have a higher risk of retiring due to disability than their “early bird” co-workers.

A team from the University of Oulu looked at over 12,000 people taking part in the Northern Finland Birth Cohort 1966 Study during this project. The group (6,169 boys and 5,889 girls all born in 1996) was surveyed about their work life and health once they reached the age of 46. Researchers also asked each participant about their sleep patterns to gauge which chronotype they belong to. The Finnish team split the group into three chronotypes, “morning larks” (or early birds), an average or intermediate group, and night owls.

Morning chronotypes, your early risers, tend to function better early in the morning. Night owls on the other hand are sharper during the evening and generally stay up later. Unfortunately, owls usually don’t go to bed early enough to get the recommended amount of rest (at least seven hours) on work nights. Researchers say this leaves them with a “sleep debt” and a need to catch up on sleep during their off days.

The results find this preference not only impacts work performance throughout a person’s career, but can also negatively affect health due to lack of sleep. Previous studies have also discovered that sleep deprivation can lead to poor physical and mental health.

The difference in performance is like ‘night and day’

During the surveys, participants also rated how they feel they perform at work on a scale of 0-10. Researchers linked all this data with the country’s registries for social security and pension payments.

Out of the 12,058 people at the beginning of the study, researchers had full details on 2,672 men and 3,159 women working in 2012. Using that group, the Finnish team examined their health over the next four years to see who had stopped working and needed to claim a disability pension. Over that span, 84 participants started receiving disability. Seventeen people died, although only three were part of the disability group.

Among men, researchers discovered 46 percent considered themselves early birds, 44 percent were intermediate, and 10 percent were night owls. For women, the numbers were 44 percent, 44 percent, and 12 percent, respectively.

When comparing early birds and night owls, those who stay up late had worse ratings when looking at both sleep and health. Night owls sleep for shorter periods of time, more often suffer from insomnia, and have high levels of “social jet lag.” Study authors add these individuals are also more likely to be unmarried and out of work.

Overall, the study finds 28 percent of men and 24 percent of women who classify as night owls underperformed at work at age 46. These are noticeably higher numbers than both morning and intermediate chronotypes. The results remained constant even when factoring for sleep length and each person’s working hours.

Late nights may lead to disability later on

During the four-year follow-up, study authors also found that underperforming at work also has a connection to higher rates of disability claims among workers. The results find male night owls are three times more likely to need a disability pension than male larks. However, these results have a much weaker connection after factoring in each person’s sleep and work schedules.

“We suggest chronotype be taken into account in supporting [work performance], both in individual-level health promotion and organizational-level planning of work schedules,” the researchers write in a media release.

Study authors add that, no matter when they sleep, it’s important for night owls to get enough sleep each night and find a work schedule which best fits their chronotype.

The study appears in the journal Occupational & Environmental Medicine.

About Chris Melore

Chris Melore has been a writer, researcher, editor, and producer in the New York-area since 2006. He won a local Emmy award for his work in sports television in 2011.

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