Comment by notacoward

That might be possible with good blackout curtains, except for the LEDs on damn near everything. Even in my own room at home, I have to remember to cover the USB charger that I use for laptop and random other devices. When I travel, it's a nightmare - clock radios, TVs, microwaves, and especially the lights built in to many GFCI outlets in bathrooms. I used to bring a roll of electrical tape for exactly this reason. Masks are the solution that works everywhere to block light, though they're less than ideal in other ways.