A team of geneticists has clocked genetic differences between "day larks" and "night owls."
Based on analysis of a fruit fly, the scientists have discovered nearly 80 genes associated with "morningness and eveningness."
Researcher Eran Tauber said that most people find that their performance is at peak at specific times of day. A great variation in this diurnal preference is found, from larks to late night owls. The impact of this preference "chronotype" on health and behaviour is well documented, but molecular basis is largely unknown.
Tauber added that most of these genes that they have identified in flies are present in the mammalian genome and would therefore be useful starting points for research in human. For example, a relatively large number of genes were associated with a molecular signalling pathway called MAPK which is also present in human and is implicated in the development of many cancers.
Tauber noted that for many, life is mainly spent indoors, so they are no longer exposed to the natural variations in light and temperature that characterise the day-night cycle. To make matters even worse, the rhythm of life is such that for many people the economic or social call to start a new day comes hours before the endogenous call from the body clock.
The combined effect of these two lifestyles causes a discrepancy between internal and external timing which, can be more or less pronounced for late rising owl or early rising lark chronotypes. This creates a clock dysfunction that is not only reflected in temporal disorientation and sleep problems, but also in conditions such as obesity, mental illness, cardiovascular disease and cancer.
As per Tauber, this study is the first stepping stone to identifying which genes are involved in this process. This will allow better diagnostics, and ultimately personal medicine, where larks and owls will receive their tailored therapies.
The study is published in the journal Frontiers in Neurology.
