Working on my sleep even more now, I’ve just had a spree of ideas, which seem to work:
Firstly I’m surprised, not sure yet, but taking an afternoon nap of 45’ has been followed by a very good night’s sleep with only 3 short breaks.
More sure about these, to do in bed while trying to get (back) to sleep:
Feeling hot: not changing blankets (too much effort), just turning them, cold side in, as much as nec…
Restlessness, esp. from the lower back:
Cobra-position as long as it takes, but that takes some effort, so wakes you up a bit.
Cat-/cow-position, arch and round back, but just lying on your side or back, so no big effort, 2x4x (= 4x each way).
Lying on 1 leg, twisting the other to the back and to the front, 2x4x.
Super-Twist: Lying face-down, keep legs there, but twist torso as far as possible “180°”, 2x4x.
Stiffness - A game-changer?
Before changing position (mainly “getting up” after sitting or lying down):
Twist both arms and legs outwards & inwards, 2x4x. Careful tho, doing it too strongly may be too much. Also with neck back when you turn everything outwards, and to the front when inwards, like lying with your back on a ball, then front, 2x4x.
This has helped me before getting up from lying at night, from sitting (used it first time in a bus yesterday), makes back exercises easier in the morning, etc.
The difference of my way is doing it without getting up in any way, just turning while lying (or sitting) down, plus keeping it quick & short.
I wanted to summarize these ideas as micro-yoga, seeing as they are quick & short, but that’s already taken, so perhaps nano-yoga, 
Oh no, that exists too… and is still longer than what I’m talking about, so: piko/pico-yoga? That just seems the name of a few yoga schools…
http://yogasimplified.com/7-sukshma-yoga-micro-yoga-exercises
My inspirations: realizing that everything I do needs to be quick & short, reading somewhere to stretch 5’ before doing something, can’t remember exactly, the idea of my acupressurist to let my knees fall to each side a few times and then rock the spine, which didn’t work tho, trying the cobra at night a couple of times against the seemlingly restless legs/back (hope this saves me from having to try Levodopa). The fast-twisting to alleviate stiffness came to me in a bus, self-consciously sitting on the disabled seats for 30mins…