I have a sitting room-turned-guest room, and with summer going into full bore the room brightens up too early in the day for sound sleep. It has become a problem. The room has several large windows currently with translucent cellular shades (I think that's the right term. One piece blinds, corrugated) and they are not dark enough.
What would be a good temporary solution to this problem? I don't want anything permanent fixed on the wall. What kind of curtains or shades or blinds or shutters can be used over the existing cellular shades? There is no protruding window frames. The windows look like these (my shades are thinner and more translucent)
One row of windows rounds a corner like these