It actually isn't, because most home lighting is far less intense than the sun and the wrong spectrum to boot. Light therapy works but sitting in front of a big bright box is not terribly convenient or fun.
And if your blackout curtains don't work, get better ones. Many Nordic households have double curtains, one solid plastic to block the vast majority of the light and the other from cloth to diffuse/block the rest and look pretty.
No it isn't. Sunlight is an important source of Vitamin D, which affects immune system, hormones, and mood. There are special lamps to supplement this, but it is not so trivial as turning on "lights".
You want “ Blackout EZ - Total Sunlight Blocking Window Covers” (available on Amazon) which seal to Velcro strips that are mounted around your windows with screws, and a DIY hard shell window valence above that, plus blackout curtains over that just so it doesn’t look so stark. That’s what I do.
One of my best investments ever was a good sleeping mask. These do not let any light in (even around the edges if it's a good fit), and unlike blackout curtains they're portable.
I'm curious to try a solution such as electrochromic glass, but to get a better blackout the glass seems to need to be tinted. But on the Dreamliner plane, they seem to have solved this. Not sure if it's just uneconomical at a house scale.
