What long term effects does taking diphenhydramine have?

Okay…for the past few months since my senior year of high school ended (08!) I have been taking diphenhydramine HCL (the cvs brand 25mg) so that I can easily go to sleep when I feel like it instead of having to deal with all the problems I have. Lately, I have been taking maybe like 3-6 pills a day ever since I left the college I was going to go to and since my sister has a boyfriend and since my BFF is like three hours away and I dont have any friends. All it seems like people talk about is my sister and her having a boyfriend so when he was over here the other day, I took like 8 of those pills and slept almost the whole day from like 5 til 1am when at 1am I woke up b/c everyone started talking loud. I know I dont have a problem but I would like to know what are the effects of me taking too many like maybe 4 a day whenever I do get really depressed and the long term effects? I can fall asleep without them at my normal bedtime but I take them b/c I dont like dealing with how things are going and such. Please let me know.