We just moved and of course didn't notice until our first night sleeping there that there is a street light right outside our window! So basically, it's pure daylight all night long. I shopped around and decided on these curtains, hoping for the best. Well, we were not disappointed as they really do block out 100 of the light. The only issues were light coming in the sides but that was fixed by velcro-ing the curtains to the wall. Now it is completely dark all night long and we love it!