I know this gland "shutters" when you look at the sun directly and you may also get this effect from using the anointing oils/topknot formula. Also once enlightened this gland will vibrate at bedtime and also when your near a baby.
I am not sure if it determins the color of the skin based on the amount of sunlight. I know people are all differant with this and I am still thinking I once read it has to do with the adrenals, but it has been along time since I read about it. My children are all differant, our 8 year old has always taned VERY DARK during swimming lessons, my Dad always tanned very dark. I have not tanned dark for many years and I have to work in the sun daily for a long time to get a really dark tan.
I use to burn easily as a child, but as an adult it seems like each year I burn less and less and rarely ever peel anymore.