Unless I am travelling I also have no sleep pattern. I go to bed when I am tired and wake up when my body tells me to. When I start waking up after nightfall (so around 4pm in the winter or later in the summer) I pull an all nighter to reset myself, I am then good for a couple of weeks. But I normally wake up a little later every day.
I’ve tried setting an alarm clock every day for the same time but then I cant sleep at night and I find myself getting more and more sleep deprived until I can no longer function.