I don't know why, but I have been waking up in the middle of the night for the past two nights. Could it have something to do with the transformation into the summer time mixing up my rhythm or something.
It's annoying. When I woke up, around 2 o'clock, I felt fully rested. I could have jumped up from bed and started doing something productive right away. But I knew better. I hadn't got enough sleep yet, so that would have been foolish. Or at least led me to be tired during the day. I could have also just done something for those couple of hours I stayed awake anyway. But I didn't want to interrupt my wife's sleep. So I just laid there with my thoughts. Eventually the I fell asleep again.
In the morning I woke up later than I had planned. I didn't even get up when the alarm went off. Despite all this I'm still tired, more tired than I was in the middle of the night when I first woke up. Maybe I should have stayed up from there after all if this extra sleep just made me more tired.