I used to be a world class 10 hour a night sleeper but since PD, I am a 4 hour at a time sleeper. Nothing seems to fix the problem completely but, I have found a few things that help. I bought an over the counter Ibuprophin PM. The PM part is Benadryl. The instructions say to take two, but I only take one. It seems to get me a couple of extra hours of sleep without being groggy in the morning as I was when I tried prescription sleeping pills. I got a memory foam 4" topper for my bed. I got extra pillows to prop up sore and stiff joints. I got an air purifier for my bedroom. Lastly, I examined my bedclothes. I found that certain styles of bedclothes seemed to get uncomfortably balled up as I tossed and turned, causing me to wake up. Everyone to his own choice but, I found that sleeping without bedclothes was the best for me.
Finally, I must say that there is no doubt in my mind that stress is a huge factor. All I can say is that when I am on vacation in a peaceful place, I get a great night's sleep.