long term side effects

I have been on elavil for about 8 years and I take 10 mg a night. Have there been any reported long time side effects? I have been experiencing different symptoms for the past year and I was pondering going off of this. Seems as if I am in such a deep sleep that in the middle of the night sometimes I wake up gasping for breath and each and every time that I did not take this it did not happen, I do like that sleep that it alows me to get Just wondering if there were any long term effects