The human body literally glows, emitting a visible light in extremely small quantities at levels that rise and fall with the day, scientists now reveal.

In fact, virtually all living creatures emit very weak light, which is thought to be a byproduct of biochemical reactions involving free radicals.

The researchers found the body glow rose and fell over the day, with its lowest point at 10 a.m. and its peak at 4 p.m., dropping gradually after that. These findings suggest there is light emission linked to our body clocks, most likely due to how our metabolic rhythms fluctuate over the course of the day.