With respect to this idea, I'm not particularly interested in either of those goals. More the general longevity and health improvements that come with regular exercise irrespective of weight loss or muscle gain [1].

I haven't been able to find much in the way of research on the tolerability of EMS during sleep. I would be surprised if the idea is actually feasible. It just seems like it would be such a big win if it was.

Personally, I frequently toss and turn and breath heavily, and wake up with a high heart rate. But then, my sleep quality is terrible and when I got a sleep study the sleep phase diagram looked like a seismograph reading during a 4 hour long earthquake, so...

1: https://theconversation.com/exercise-extends-life-even-witho... (Maybe not a great source but I think there is a wealth of evidence for this)

Ok well here is a general longevity-related reason why resistance training is important.

Lifting weights also increases bone mass. As you get older, osteoporosis becomes more and more of a concern. You fall one day, and the less bone mass you have built up, the more likely it is that you will lose mobility. There is a strong link between reduced mobility and cognitive decline and also a cascade of other health problems. Old person + hip fracture = significantly increased mortality, and the way to prevent this is by building up bone mass while you still can.

I hear some people fix their sleep problems by staying awake much longer for some days then follow a strict schedule.

For me, after physical activity sleeping is much easier but if i over do it cortisol wil make it worse. (I once created an exercise formula that kept me awake long enough I started hallucinating) Spinach does miracles for me, the magnesium folate and flavonoids lower cortisol. Popeye was apparently on to something.

YMMV