First, breathing. For starters, you shouldn’t drown, for which you either have to be strongly fixed in a position with face up out of the liquid (which will be super uncomfy), or you should depend on oxygen mask (which is very dangerous when you’re unconscious during sleep)
Second, skin breathes too - and in liquids, the pores close and skin can’t breathe - which will eventually lead to hypoxia even if you breathe normally.
Third, skin gets irritated and damaged at prolonged contact (like, you know, 8 hours of sleep a day) with just about any liquid. It should be insanely inert.
Fourth - the thermal conductivity of such liquid should ideally be the same as air - too much (which is just about any liquid) would be harmful for your body’s thermal regulation and, again, for skin, too little would make you overheat.
Fifth - you need a liquid in which you can be suspended, which is impossible to precisely measure since our buoyancy constantly changes due to us breathing, and our breathing patterns change as we move between phases of sleep.
TL;DR - There’s a reason all those vats are part of sci-fi: as cool as they look, they are insanely impractical.
There’s quite a lot of issues with that, too.
First, breathing. For starters, you shouldn’t drown, for which you either have to be strongly fixed in a position with face up out of the liquid (which will be super uncomfy), or you should depend on oxygen mask (which is very dangerous when you’re unconscious during sleep)
Second, skin breathes too - and in liquids, the pores close and skin can’t breathe - which will eventually lead to hypoxia even if you breathe normally.
Third, skin gets irritated and damaged at prolonged contact (like, you know, 8 hours of sleep a day) with just about any liquid. It should be insanely inert.
Fourth - the thermal conductivity of such liquid should ideally be the same as air - too much (which is just about any liquid) would be harmful for your body’s thermal regulation and, again, for skin, too little would make you overheat.
Fifth - you need a liquid in which you can be suspended, which is impossible to precisely measure since our buoyancy constantly changes due to us breathing, and our breathing patterns change as we move between phases of sleep.
TL;DR - There’s a reason all those vats are part of sci-fi: as cool as they look, they are insanely impractical.