Even if you are fortunate enough not to be beaten up, there are more pleasant things to do with your time than standing on a platform waiting for a tube train at midnight. Waiting for any form of public transport at midnight, especially if it is cold, is not everyone's favourite thing to do. At that time of night, unless you live in a city that makes a choice to keep the same service frequency until it stops (like Zurich), you can potentially have a bit of a long wait.
All of us have at one time or the other had to work late. It is nice to get home finally.
I had to stay late last night for a meeting and took the bike home in the dark. I have to say there is something to be said for travelling that way. I sit and whinge repeatedly at the lack of decent cycling infrastructure, at having to share the road with fast moving cars that too often pass by too close, and at the many obstacles on my way that seem to be placed there to make life difficult.
You forget all of that though when you ride at night. It is the best way to travel. There is little traffic, you have that cool autumn breeze in your face (though not in your hair alas) and you can smell what people are cooking for dinner. Speeding through the darkness by yourself is a great way to clear your head. Plus, nobody hears you when you sing along with your iPod.
(Picture from The Girl in the Cafe - great pictures of London)