As someone mentioned, I would wonder if the fleece might stretch? Also, would think it'd block a fair amount of the light from coming in.

It'd sure do the job. I was raised in an old farm house, and Mom always had winter curtains that were heavier, then some light lacy ones for the summer.

Rather than fleece blankets, what about buying the yardage?

Not sure what length/height you need, but if you bought the fleece and turned it sideways, you could have one continuous piece.

That sounds like a good idea. DH and I both work nights and day sleeping can be hard sometimes. Fleece would help warm the room and keep it darker, so it would be a win-win solution.

Last winter I hung fleece blankets behind the curtains in dd room. Helped a lot

My living room curtains are very thin. (need to buy new ones) Last year I hung fleece blankets behind them worked great. I will have to do that again this year. I can not find anything I like.

My long arm is in a 3 seasons room. Although we added a heat pump for heating and cooling, all the windows are an issue. I,ve got plans to make quilted curtains, and was going to use fleece for the batting. This way there should be no sagging.

I have window quilts. They're decorative and can be changed with the holidays. Put a small rod pocket on the back for a tension rod.

I hang a fleece blanket in my stairway to keep all the heat from going upstairs and it works great.