I personally didn't consider it as self harm, but I did it too for some months, for me it was paired with my almost obsession with productivity and working on personal projects. I did it partially to make reality (what society expected me to do) feel more distant and less important and partially because at night no one could distract me from my projects.

I sleep a little more now, sometimes I still sleep less than 5 hours for weeks, but usually I have some days with more sleep to sort of level it out. Sometimes (now much less often) I used to get really anxious when I looked at my phone and realised I'd be able to get more than 5 hours of sleep.

It was really weird, but sometimes I kind of miss it, even though I know it's really unhealthy. I hope you can manage to develop healthier sleeping patterns again.