Early risers felt less sleepy, and had faster reaction times, than night owls throughout the workday.

Most people have a “circadian phenotype” – otherwise known as a sleep-wake cycle. It’s your innate, biological preference for waking up at a certain time and feeling sleepy at another. And you’ve no doubt heard of night owls and morning larks – who operate on vastly different sleep schedules.

The world can seem a little unfair for night owls, because it’s often geared to the preferences of early risers, for example school and working days traditionally start at nine. Previous research has shown that this misalignment of professional life with the internal schedule of a night owl can lead to poor mental health and increased risk of chronic conditions like cancer.

In this research, 38 people (who were either morning larks or night owls) underwent MRI scans and completed a number of testing sessions between 8am and 8pm to see how well their brain functioned at different times of day. They were also asked their level of sleepiness at various points in the day.

The researchers found that morning larks said they were least sleepy, and had the fastest reaction time, in the tests that were done in the morning. That’s to be expected.

And night owls had the fastest reaction time, and said they were least sleepy, during the evening test. But even in the evening tests, night owls didn’t have significantly faster reaction times than the morning larks.

The brain connectivity in those regions of the brain which are linked to low sleepiness and better performance were higher in the morning larks throughout the entire working day, suggesting they generally have an advantage.

Implications

It’s a tough world for the night owls when the structures of school and work are stacked against them.

If you feel you’re significantly impacted by your chronotype, it might be possible to implement flexible working hours with your employer. And research continues into how best to adapt schools and workplaces to suit the needs of (and get the best performance from) different chronotypes.

Last Reviewed: 21/01/2020

© Norman Swan Medical Communications.



References

For reference: Facer-Childs, et al (2019). Circadian phenotype impacts the brain’s resting state functional connectivity, attentional performance and sleepiness. Sleep doi: 10.1093/sleep/zsz033.