Could we solve the global obesity crisis by turning out the lights?
A provocative paper published Wednesday evening makes the case that the rising incidence of obesity worldwide may be linked to the disruption of our bodies’ circadian rhythms caused by the growing presence of artificial lighting.
Writing in the journal BioEssays, Cathy Wyse, a chronobiologist at the University of Aberdeen in Australia, explains that the human body, like those of other species, is governed by circadian rhythms, a set of mental, physical and behavioral changes designed to be finely tuned to the variations in natural sunlight and darkness throughout the day and night.
Circadian rhythms, which vary from person to person and likely have a genetic component, follow a 24-hour cycle. Their disruption has been tied to sleep disorders and some mental illnesses such as depression and bipolar disorder, according to this fact sheet from the National Institutes of Health.
The advent of artificial light in the late 19th century brought disruptions to circadian rhythms, exposing people to light at times of day when their bodily and mental functions expect darkness and causing what chronobiologists call “circadian desynchrony.” Artificial lighting also has made shift work more possible, which has in turn altered people’s sleep and eating schedules, Wyse notes.