You really do not want to deplete batteries on devices where they're difficult to replace. Whether that is true for your sleep mask, I HAVE NO IDEA. A better way to deal with it is have them disable themselves after a timer. Maybe you can enforce that from the other side (I assume that is your smartphone?). Like, you can do some device automation with e.g. MacroDroid.
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You really do not want to deplete batteries on devices where they're difficult to replace. Whether that is true for your sleep mask, I HAVE NO IDEA. A better way to deal with it is have them disable themselves after a timer. Maybe you can enforce that from the other side (I assume that is your smartphone?). Like, you can do some device automation with e.g. MacroDroid.