The reasons.

The reasons are very simple. There was no time. That actually means, I guess, I didn't take the time. But no! Why not make something else responsible: my internship. That was pretty intense, indeed. Most days (lateron I overslept) I arrived at half past 8, which required me to get up at half past 6. (I guess, I already wrote about that. Perhaps I'm just fascinated that it's possible to get up that early.) And then I started to take the last train home and entered my parents' house at quarter past 12. So there was no time, right?
Why was that internship this crazy?! Well, most importantly: it was a lot of fun -- otherwise I hadn't spent soo much time there. And secondly: it seemed necessary; we started that project and time pressed. But in spite of the stress, or maybe even because of it: it was really, really exciting and I enjoyed it a lot. (I'm actually too lazy to tell you about the research we did there in detail. I can make some general remarks upon request, though.)
But I really do hope, that these conditions (in terms of working hours) won't reoccur later in my life. (--> So there are good chances that the blog won't be deserted ever again! ;-))