When your mom says "Go, play outside!" she intuitively knows whats good for you without being able to explain the biological background. Now scientists showed how natural daylight vs artificial light can improve glucose metabolism in patients with Diabetes type 2. Participants either sat in a room with large windows, or in a room with no windows but a lamp. After exposure to natural light, glucose homeostasis improved. Expression of important genes regulating the circadian rhythm was higher and levels of the sleep hormon melatonin were also higher in the evening indicating that natural light improves sleep quality Since many individuals nowadays spend most of their time indoors, this might be the straw that breaks the camels back for some pre-diabetics.