I was diagnosed with PD in 2018. Tak Sastravi 5x daytime. I’ve experienced clear effects of SB (sleeping benefit) until November, but have since decreased. My amateurish impression is that SB is primarily obtained during “deep sleep” (which daily hard training/exercise is likely to support).

No, there’s no definite scientific evidence for how the sleep benefit works — but it’s a well-known phenomenon in some, but far from everyone, with Parkinson’s disease. There are theories that dopamine is formed and stored during sleep and not consumed in the same way as during the day, and another theory that it’s some kind of a daytime rhythm mechanism.