I woke up at 11 am on Saturday.

"Christ!" I thought, "I'm going to be late for work". Then I realised there is no work on Saturday.

I woke up yesterday at 4 pm. "4 pm? Shit. I've missed work". I stumbled out of bed, thinking "No time for a shower!", got dressed and opened the curtains to reveal complete darkness. I went back to bed and got up five hours later, at 9 am.

What, exactly, is going on with my sleeping patterns?