I heard this first-hand from a therapist though I didn't know if I really believed it at first. He said there were these breakthrough studies done that showed light- even artificial light (as opposed to natural daylight)- made a HUGE difference in helping rid depression, not just a little one like common sense would dictate. Also I notice my mom emphasizing opening the blinds more than usual in the day and it isn't till now I realize why she does this. I eventually noticed the difference light made in my depression as well. So light both artificial and natural really do impact how depressed you are or aren't.

So if your feeling down, get some light!

(And laughter. Studies done have shown laughter is good for you too).

You body needs sunlight to produce certain vitamins (D is one of them). That's why even going outside with too much sun screen can mess this process up.

The process has to do with the amount of light your brain senses.
Summertime, there is more light and is associated more with activities and fun.
Wintertime, there is less light and is associated with leaves falling off trees and birds flying away
and a host of other things which helps trigger and/or extend depression.

live long and prosper

no wonder sometimes I feel less depressed with more light when I read at night