If that's the case then being powered off means that they don't dream. I imagine they close their eyes. And for what seems one second passes and they turn on again and a few hours already passed. Might seem disconcerting at first but comparatively as humans we dream and we can tell if we did even if we don't remember much. For Exos I imagine it's a continuous stream of consciousness with virtually no "rest" or dreams in between.

Anytime! -I've been thinking about their recharge cycles. How do they do it? Do they power down and then just collect energy like photovoltaic batteries? Do they literally plug in to recharge the batteries? Would that limit the range of Exo travelers? (Guardians not withstanding.)