Night owls have shorter clock gene

Some people can burn the midnight oil, while others might prefer to tackle their challenges early in the morning. Although most people know instinctively if they are an ‘evening’ or ‘morning’ person, scientists have now discovered why we fall into a certain category.

Scientists at the University of Surrey, in co-operation with clinical colleagues at St Thomas’’s Hospital (London) and Hospital de Gelderse Vallei (Netherlands), have discovered a correlation between a difference in the length of a so-called clock gene and morning or evening preference. This study is the first reported correlation between individuals with an extreme evening preference and variability in a specific gene. The gene, Period 3 (Per3), forms part of the clock genes that create our internal body clock. Per3 has two variants, one shorter and one longer.

Dr Simon Archer, lead author of the paper said of the findings: “We discovered that the shorter variant of the gene is significantly more common in people with an extreme evening preference. This is even more so in patients suffering from delayed sleep phase syndrome, a sleep disorder where people fall asleep at very late times and have difficulty waking up in the morning.”

Professor Jo Arendt, senior member of the team, said “It is tempting to speculate that one day some people might choose their lifestyle according to their clock genes.”

Dr Malcolm von Schantz, senior author, concluded: “There are at least ten of these clock genes and there are differences between these genes. Whether you are a night owl or a morning person is determined by the sum of these differences.”