I didn't spec 1G of force. Though, as I, ahem, already said, I do suspect we'll need closer to .5G than .05G. But while it's not quite as evil as the rocket equation, you do get non-linear advantages as you go down the gravity scale. .5 is already much less than half as hard as 1G, and we could perhaps get away with .25.
Here we have a chicken and egg problem; how can we launch the variable-speed lab we really need to figure out how much gravity we need if we can't afford the 1G lab in the first place? Because proper science suggests we ought to be able to test the full range up to 1G. I'm spitballing .5 or .25, but scientifically speaking there's no guarantee the optimal won't be .8, 1.0, or, conceivably, even 1.1 or 1.2G. (Sure, the latter is unlikely, but I can't scientifically rule it out a priori.)
If it was possible to build a gravity sleep chamber, it's very possible that exposing the human body to gravity and zero-gravity on a daily basis would be put more, not less stress on a body than zero-gravity alone.
That's just a random guess. We already lay down for 8 hours and stand up for 16. My random guess is, our fluids would recover with at least some artificial acceleration and why not when sleeping?
Here we have a chicken and egg problem; how can we launch the variable-speed lab we really need to figure out how much gravity we need if we can't afford the 1G lab in the first place? Because proper science suggests we ought to be able to test the full range up to 1G. I'm spitballing .5 or .25, but scientifically speaking there's no guarantee the optimal won't be .8, 1.0, or, conceivably, even 1.1 or 1.2G. (Sure, the latter is unlikely, but I can't scientifically rule it out a priori.)