They block out 100% of the outside light since I am a super light sleeper so these help so much! They are  very thick and nice ,They also have weight to them without being too heavy. These curtains are extremely nice. When I opened them they were soft, suade feeling. They hang nicely and the wrinkles came out quick just by letting them hang for a day or two.    They keep out alot of heat that we have here in Texas, so that helps on the electric bill as i dont have to run the ac near as much.