I have now been practising Yoga Nidra guided meditations for around 3 months at the time of writing this, daily each morning. I definitely have seen cumulative benefits for progressive reduction of my Parkinson's Disease symptoms over that time, including much reduced anxiety, pain, less really bad days. However, in particular, I’ve noted increased effectiveness of dopamine replacement drugs, longer "on" periods, as well as improved sleep. Indeed, I personally believe that the practice does indeed boost my dopamine levels, because when I take a dose of my PD meds after or during a Yoga Nidra session, it is much more likely that that dose will actually work to turn my movement back on, and it can take as little as 15-20 minutes for the drug to kick in (this is very short time for me, about 50% less time needed than usual.