Exposure to light through the eyes helps regulate the body’s sleep/wake cycle by affecting the pineal gland’s secretion of melatonin.
This hormone is produced at night and promotes drowsiness; exposure to light, notably blue light, suppresses it.
This is one way sunlight contributes to alertness, and why lack of light at night helps increase sleepiness.
http://www.wellnessletter.com/ucberkeley/feature/it%E2%80%99s-late-turn-off-that-computer/#
download this free app http://stereopsis.com/flux/ to regualte the ‘blue light’ to an ‘amber’ on your ipad, desktop, or smartphone screen.
Sweet dreams!
Krista Lynn Reid