Whether it’s a lightbulb or a backlit screen, artificial light sources make it easy to read, work, inform and entertain ourselves when the sun has set.
But having light at the flick of a switch is a relatively new situation in human history, and the evidence is mounting up that artificial light can disrupt our internal “circadian” rhythms, which in turn are linked with our health.
A recent paper in the Annals of Medicine notes that "…artificial lighting might initiate metabolic disruption and contribute to the association between global urbanisation and obesity."
While the evidence reviewed by the paper is supports an association between artificial night-light and metabolic dysfunction, it is not enough to say whether the link is causal. Still, it’s worth seeing for yourself whether you sleep and feel better if you get some sleep instead of staying up too late courtesy of the light from a screen or bulb.