I taught psychology at the high school level and one of the subjects we looked at was artificial light and its effects on our lives.
Back in the day people went by the sun up sun down cycle for activity. It is no longer necessary to stop anything because it is dark - including eating, watching TV, or spending time at the computer. Our sleeping habits have gotten out of "sync". Many who are struggling often struggle with eating at night or in the front of the TV.
Ever had jet lag? Do you know about your circadian rhythm? Ever known someone who works third shift or perhaps you have had to endure this.
Info. on circadian rhythm - http://www.psychologytoday.com/basics/circadian-rhythm
We visited my husband's brother in Alaska during the daylight 6 months of the year. I didn't know when to sleep. I didn't know what day it was. There was no real night. The windows has to be completely covered so I would think it was night and could sleep. They have a real problem in Alaska with SAD (seasonal affective disorder) - suicide is bad there because of depression. It is recommended to use the lights that simulate daylight. There is also a high rate of alcoholism there.
I think I read that 20 minutes of sunlight is enough for our daily need of Vitamin D. Indiana gets pretty gloomy for long periods of time during the winter months. Perhaps this contributes to SAD because I know people in the Midwest suffer from it as well as in Alaska.
Can you tell the days are getting shorter? I can here in Indiana. It's almost 7 a.m. and it is just a dusk kind of light outside. I need to water things with the hose and have to wait until I can see what I am doing.
Can you identify with any of this?