HI. I Have Graves Disease And I Have Been Taking

HI. I have Graves disease and I have been taking Unisom for many years. I notice that my symptoms of Graves get worse at night after I go to bed. I think that even though I do have Graves, the diphenhydramine may be making me have arrythmia (sp?) and maybe other symptoms, or maybe even caused the Graves? I try going off the Unisom, (I only take a quarter of a tablet) and I can't sleep, so I end up getting up and taking it so I can be rested for work. How does diphenhydramine effect the thyroid?