Skimming the original study, it talks about subjects opening and closing their eyes, so I would very much assume that it's entirely related to seeing light (and not about absorbing light through the face or body).
If you get a sleep mask, be sure to look for one designed to not put pressure on your eyes, which are not hard to find if you seek it out. The cheap ones you get at pharmacies and dollar stores put direct pressure on the eyeballs and it's a wonder that anyone can tolerate them and are perhaps even harmful.
If you get a sleep mask, be sure to look for one designed to not put pressure on your eyes, which are not hard to find if you seek it out. The cheap ones you get at pharmacies and dollar stores put direct pressure on the eyeballs and it's a wonder that anyone can tolerate them and are perhaps even harmful.