Review (5/5): Best Sleep You'll Ever Get
I highly recommend the Earth Therapeutic sleep mask. It's nicely padded to block out light but doesn't have the annoying "roll" that some sleep masks do. The adjustable velcro-elastic band holds the mask securely in place without being uncomfortable. The width of the elastic is such that it doesn't leave a "notch" in your hair.
I've been using this brand of sleep masks for several years now and won't use any other brand. In fact, I now keep one by the bed and one in my overnight kit. I can't sleep without them now.