The original plan was, as soon as my class was over at 16:15, to jump into my running clothes, take the S-Bahn to Adlershof, and run my 30K route back home, meeting Hannah at 15K. Although I made it to the start right on time, the reality was that it got darker much sooner than I thought, and Hannah was busy so asked if she could meet me at 20K for a 10K run home instead. It turned out anyway that from 13K to 20K (GHO) I ran in complete darkness except for the quick run through Lichtenrade. My running headlamp was absolutely mandatory along the former Berlin Wall route, again creating a spooky Blair-Witch atmosphere illuminating the bushes and trees at night. Interesting was being able to see from there the planes taking off from the new BER airport into the night sky.
When I finally arrived at GHO to meet Hannah, it was ridiculously clear that it was far too dark for her to run the 10K Berlin-Wall route home, since at this point after my 20K she was faster than me and without a headlamp, and so we took off instead on a 5K route home along the M82 route, Hannah very quickly sprinting out of a sight, much too fast for my 20K legs. I noticed that even on the lit sidewalks my headlamp came in handy for illuminating patches of shadows so that you could better tell where you were running, so eventually bought Hannah a headlamp as well for such occasions. These lamps have three levels: low = 50 hours, standard = 3 hours, and Max power = 2 hours. To light up dark areas of lit sidewalks, you really need the max power on, but to illuminate absolute darkness to see where you are going, the low setting is enough so that you can at least see where the path is, etc.