The house behind us has a seriously bright light that is kept on ALL NIGHT LONG! Drives us insane and prevents my other half from sleeping half the time. After many-a-nights of complaining, I finally fixed the shade. The first photo shows what the shades look like during the day. These things don't block out all that much light. In this pic, you can completely see our other neighbors house.
I bought some black out fabric for about $6/yard and hot glued the fabric along the top of the back of the shade. Worked perfectly and the room is now pitch black at night. This pic was taken at the same time as the first one and you can't see out at all. Hubby loves it and I love that he quit complaining about it...problem solved (see I'm an engineer at home too....).
Here's to long restful (and peaceful...and DARK) nights!