I’ve never actually used one outside of airplane long-hauls to Asia.
In my freshman year of college, I had a difficult roommate. She would go to sleep at around 9pm and I would have to keep a tiny lamp on with a cloth over it to try and get ready for bed in order not to disturb her.
Apparently, she thought this lamp of mine was unbearable, so she bought herself a sleeping mask. One would think this would solve the problem, but every night she would put it on, go to sleep, sit up in bed, TAKE OFF THE SLEEPING MASK, stare at my lamp, put it on, go to sleep, and sit up again, repeatedly. I really don’t know why she bought one if that was what she was going to do with it.
In the end, I just moved a lot of my toiletries to my best friend’s dorm room, where she and her roommate slept at the far more reasonable time of 1am.