My spouse just cannot sleep if there is a shred of light in the room. It have to be total darkness. After a strings of failures and frustratio, we found some ways to accomplish that.

Nicer way: plantation indoor shutters with Amazon basic blackout curtains.

Cheaper way: put a cardboard box (preferably white) on the window and add Amazon basic blackout curtains. Cut the cardboard by measurement so it fit perfectly on the window (i could just slide it in on my windows without tapes but my brother had to put tape so it stayed).

Ghetto way: garbage bags and amazon basic blackout curtains. Tape black garbage bags together (two garbage bags on top of each other is needed) by the size you needs. Always put the garbage bags bigger then your windows' trims by about 3-4 inch so the sunlight don't creep out on the side. Tape the garbage bags to the window trims. I likes to tape only the top so I can opened it in the morning by rolling and sticking it behind the curtain rods to hold it in place. Easy to unroll it and put it back to cover the window).

Amazon basic room darkening blackout window curtains were the best I found. An example: https://www.amazon.com/AmazonBasics-Blackout-Curtain-2-Pack-66x72/dp/B071NVVS2J/ref=mp_s_a_1_12?crid=C939HGIGAV4N&keywords=amazon+basic+blackout+curtains&qid=1674871862&sprefix=amazon+basic+blackoit+curt%2Caps%2C144&sr=8-12