Early bird or night owl? New BioClock research reveals that light sensitivity plays a big role

Light is one of the most powerful signals synchronizing our biological clock to the outside world, but people differ widely in how sensitive they are to light. A new BioClock study, recently published in SLEEP, takes a closer look at how these individual differences in light sensitivity relate to chronotype – whether someone is naturally an ‘early bird’ or a ‘night owl’.

The BioClock research team, led by Dr Laura Kervezee, conducted this ambitious study at the NEMO Science Museum in Amsterdam, where they managed to include almost six hundred children and adults. Participants completed a short questionnaire about their sleeping habits and underwent a pupil test that measured their pupil response to flashes of blue and red light. This measurement allows researchers to determine the light sensitivity of the cells in our retina that send signals to our biological clock.

Their findings?

In adults, the relationship between light sensitivity and chronotype depends strongly on both age and sex. Young men with higher light sensitivity tended to be evening people, compared to those with lower light sensitivity. Meanwhile, older women with the same light sensitivity tended to be morning people. In children, no link was found between light sensitivity and chronotype, suggesting this relationship emerges later in life.

What this means

It’s clear from these results that how light affects our biological clock is influenced by who we are and how we age. These new insights into this relationship can help us better understand why biological rhythms can vary so much and provide better, personalized advice on how much light you need and when.

Bringing BioClock to the public

Not only has this study brought us valuable new scientific insights, but it has also contributed to one of BioClock’s key missions: spreading knowledge of the biological clock to the public. Conducting this work at NEMO allowed the team to engage thousands of visitors in conversations about sleep, light, and health, while simultaneously collecting high-quality data from a diverse population outside the laboratory.

Read the full article here.