NightShift Frame-Fit Blackout Blind

This is the gold standard for shift workers, and it's what I'd point anyone toward first. The side channels are what set it apart — most blackout blinds still leak light around the edges no matter how thick the fabric is, but this one runs a tension-fit frame down both sides of the window that seals it properly. Fitting takes about 15 minutes with no drilling, which matters if you're renting. If your window is a non-standard size you can trim the frame with scissors, but check your measurements twice before cutting.