Remember summer camp? "Lights out" meant time for sleep, even if you sometimes stayed up until midnight telling dirty jokes in hushed tones. On most nights, slumber came easily.
If you have trouble sleeping now that you are an adult, try putting yourself in a dark environment an hour or so before sleep time. Read with just enough light on the page, and darkness everywhere else.
|Sleep on Flights|
|Decor Advice to Enhance Sleep|
|Herbal Tips for Sleep|
Our species has been around a million years, so artificial lighting is a recent invention. Darkness is nature's original downtime cue.