Since I have east-facing windows I have been woken up quite rudely by the sun every morning around 7. I try to go back to sleep, but the blinds are crap in these apartments, and so it only gets increasingly warm and bright in my room.
I'm hoping the posters block out enough light to keep it darker, and the white backs reflect enough to keep it cooler in my room tomorrow morning.
If it works, I'm giving myself 25 points for being resourceful.