I have a bedroom that gets the full early morning sun.  Even though this curtain rod looks very different from any other curtain rod I've ever seen, I decided to give it a try.  It works fabulously well!  I do not get any light escaping where the curtain goes around the bend in the rod and touches the wall.  I do get a little bit of light from the top of the curtain however.  I have a high ceiling and hung the rod about 10" above the window frame.  It works!