As someone who struggled with insomnia for years and years, I sympathize. I was born blind, and thus have the same sort of disorder. As a teenager, I would go for days without sleeping properly, because I could only sleep during the day, but I had to go to classes during the day, and would then be awake all night. However, as an adult, I've had to find better ways of coping, in order to be part of the working world, and uphold my adult responsibilities. I'm 30, and only in the last couple years have I managed to get into, and stay on, a semi-regular sleep schedule.

The first big step for me was realizing that something, in fact, can be done. It's only recently (in the past five years or so) that people have even started talking about the sleep disorders experienced by the blind. Previously, many people in my life didn't believe me about how serious the issue was. And, of course, that lead me to doubt myself; maybe it's just me. Maybe I need to just get over it. Those are, of course, not useful coping strategies.

Later on, this evolved into "this is just my sleep schedule. It's just how I am. It will never change, and I can't do anything about it." I suspect this might be where the blind person in your life is now. He's just accepted that lack of sleep once a month is just how it is.

That's not true. I'm not a doctor, so I won't give medical advice. But I can say from personal experience, that with hard work, trial and error, and some lifestyle changes, it's possible to get on a regular sleep schedule that varies by only two or three hours. If you'd told me that five years ago though, I'd have laughed in your face. Oh, it'll never be perfect. The weeks around the time changes twice a year are pretty much a write-off for me. But it can get better.

I think the best thing you can do is encourage him that it doesn't have to be this way. For me, a combination of Melatonin, increased physical activity, a sleeping pill once a month to help reset my sleep cycle when it's drifted farther off than I'd like, and a strict bedtime routine (to give my brain queues other than light level that it's sleep time now) has helped a lot. However, his mileage may vary. But today there are medications specifically designed to help with the problem, and doctors and sleep labs are actually aware of the issues. The condition is generally called non-24 sleep disorder; having an official name is a big step forward from the days when it wasn't even recognized as a thing.

If you're willing to support him on the journey, it's likely his sleep quality can improve a lot from what he's dealing with now.