Work schedules based on biological clocks may cure 'social jetlag'

The grind of a work week can be difficult for any employee, but people with work schedules not matching their biological clocks may experience "social jetlag" or the feeling of walking around in a fog.

Researchers of Ludwig-Maximilian-University in Germany report that sleep and workers' general wellbeing could be improved if work schedules took workers' biological clocks into account.

Researcher Till Roenneberg said that a simple re-organization of shifts according to chronotype allowed workers to sleep more on workday nights. As a consequence, they were also able to sleep less on their free days due to a decreased need for compensating an accumulating sleep loss. This is a double-win situation.

Such a change might have other long-term health implications, too, although that remains to be seen. The researchers got the chance to implement their ideas about sleep and work schedules in a real-world factory setting thanks to a former labor director at ThyssenKrupp Steel Europe. He was interested in finding ways to improve workers' health and lower their stress.

Factory workers were assigned to an early, late, or intermediate chronotype based on their normal sleep patterns. Morning people were never made to work late and night owls were never forced to get up early for work. Those with an intermediate chronotype served as controls.

With those adjusted schedules, people felt more satisfied with the sleep they did get and experienced slight improvements in their general wellbeing. It also reduced social jetlag, the difference between the midpoint of workers' sleep on work versus free days, by one hour. The improvements weren't as great for those who naturally prefer to stay up late, they found, which shows that night work is hard on everyone.

The findings also show that flexible work schedules aren't just more convenient, they can really make a difference in the way we feel, and perhaps also for our long-term health.

First author Celine Vetter said that they know that sleep has important implications not only on physical health but also on mood, stress, and social interactions, so that improving sleep will most probably result in many other positive side effects.

The study appears in the Cell Press journal Current Biology.