Because the fabric is light blue, it doesn't actually block any light. It's super soft though, and it doesn't pull right around the head --which makes it feel like you aren't wearing one. If they made it with black fabric, it would easily be a five star product.
This was a gift for our daughter who has a young son...she told me it was wonderful and helped her to rest when she had the chance to during the daytime baby naps!
I love my sleep mask. I have had several others in the past but never knew how much cooler I could be by using bamboo. It makes a huge difference and is so soft.
Adult Aquamarine Bamboo Sleep Mask