I'm with you, mines illness related as I have severe Rheumatoid Arthritis and get woken up with pain at anything from 2am onwards. Once I'm awake, that's it, I'm up for painkillers and can't get back to sleep, I've been like this for about 2 years now.
I did manage to sleep till 5am today and that is huge for me, although we were out until about 9pm last night, it won't be like that tonight.
I hate it though, as in the evenings I'm asleep in the chair. I worry about my wife to be honest, as what kind of evening does it give her, having a husband asleep in the chair. She is brilliant though, never complains and just says, if you are in pain, you need the sleep, it's not your fault. She's lovely and understanding, but I do worry.
I've tried everything, taking my painkillers before bed, etc. nothing changes. It's pretty tough working, as it's exhausting, but I guess one bonus is, I work from home.
I feel for you, the nights are long and it's a lonely old time.