Needed the mask, because I can not darken enough the bedroom. The mask meets all the criteria that are important. She sits and lets almost no light through. However, what if you sleep more restless, it may be the si enicht more optimally seated, then it can happen that light coming through. Who knows the problem with lighting in the bedroom, which is really a frohs this mask to have. However, they do not wear 100%: down some light can get through depending on the seat. It could interfere with sensitive some. Allerding sist This also comes in handy, then you will be in time awake before it is woeder evening ^^. I'll All thing very well with this mask to right and am glad that I have them.