I thought I'd share a small mod for cheap sleep masks that will allow it to actually block the light under the bridge of your nose (for those like me who have never used a mask that is dark enough because of having a large nose)
Around the edge of the mask, there is usually a sewn-in banding that is supposed to aid in keeping the light out.
Very simply I loosen a stitch on the underside of the mask banding, using an awl (or a fork), and slide in a 4" piece of wire into the banding.
Now you can mold the underside of the bridge around your nose, so you get a contoured fit.
After trying light/heavy wire, I found the best one is the plastic coated one you find when buying toys/tools/appliances that are strapped to a card.
I have a collection of masks (most are freebees that come with amenity kits) and the ones I modded are all now light-tight
I've tested some of the expensive masks in various airport/travel stores that let in less light and some are really comfy, but none cater to a big schnoz like mine :^b ... so I never bothered to buy any more.