The only problem with this setup is that you will probably fall asleep more often than not when trying to work... and if you manage to get used to it you will train your brain that "lying down is for work, not for sleep" which is not good either.
When I "just work" i.e. don't do much in terms of physical activity, I can stay awake as long as I want.
Probably depends on a lot on people. At least I can certify that people falling asleep in class is a thing, and not even a small percentage.