I had to buy 100% blackout electric shades. They're simple to install and can even work in a rental apartment. (not associated with company, but they were "Yo

I had to buy 100% blackout electric shades. They're simple to install and can even work in a rental apartment. (not associated with company, but they were "Yoolax Motorized Cellular Shade" in "Blackout Pearl" on amazon, and you measure and order the shades in 1/4" increments) They came with these L-shaped light-blocker things that attach down the sides of the window opening to block light from the side. You can get a pretty dark room, but I also put a little black tape on the few remaining tiny cracks.