I also have pd fatigue but it was much worse when I was diagnosed and it first started. It was one of my early symptoms. Over the last few months its actually gotten somewhat better for the most part. I still like a 45 min nap in the afternoon when I can but some days I find I don't need it and just tell myself Im tired. I also find since Ive started exercising each day Im not as fatigued, but then there are "those days" when you just have to lay down for a bit. I also find that being stressed makes most symptoms, including fatigue, worse. Id say if you're able, nap when you feel the need, but try to start working any exercise routines you can into your day, starting a few minutes at a time.