I've been to some houses where the shutters had no gaps and they fit the window frame so well that virtually no light made it in, even during the day. It was surreal waking up in the morning, thinking it was still night time, then checking the clock only to see it was 8AM. A great feature to add to a house if you ask me.

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.

I bet that with your eyes closed, the difference between "black out blind dark" and "no light" isn't much. I bought black out blind about 5 years ago and they're amazing. If I'm in my parents house or staying in a hotel during summer, I get crappy sleep and I'm wide awake at 5am.

Thanks God I'm in Europe and we have access to alien technologies such as roller blinds, which are basically the default on anything modern