Have you ever wondered why some people leap out of bed first thing in the morning, instantly ready to tackle the day ahead, while others only start feeling productive late in the day? If so, you might be interested to know that much of the variance is controlled by genes – or, to be precise, a protein-coding gene called period circadian regulator 3 (PER3). This helps to regulate our body clocks, controlling the sleep/wake cycle or circadian rhythm.
Mutations in PER3 have led to the existence of “extreme larks” and “extreme owls”. These make up 27% and 9% of the population respectively, according to a 2018 study of 433,268 people published by Kristen Knutson and Malcolm von Schantz in The Journal of Biological and Medical Rhythm Research. Most people, who sit somewhere along a continuum between these two chronotype groups, are known as “hummingbirds”.
Evolutionary psychologists posit that the emergence of larks and owls started as a tribal protection mechanism. Night was the most dangerous time for early humans. It made sense to have people who were able to stay alert, maintain the fire and keep watch overnight. They could then be relieved at dawn by the early risers.