Why we need to sleep in total darkness

http://io9.com/why-we-need-to-sleep-in-total-darkness-1497075228?utm_campaign=socialflow_io9_facebook&utm_source=io9_facebook&utm_medium=socialflow

Whenever I have trouble sleeping it’s almost always light related.

Posted from WordPress for Android via my Samsung smartphone. Please excuse any misspellings. Ciao, Jon