I think it breaks down into two different activities; riding up to midnight, and riding midnight to dawn. The first is pretty common and good exercise after dinner. After midnight is fun, but a little weird. I did a post about my full moon solo ride, getting back around 8am. It was worth doing, but I paid for it the next day...messed with my sleep cycle [pun] and felt like crap for a couple days. And that's the issue, recovery from riding 8 hours plus not sleeping overnight is a double whammy.

My experience, safety is a non-issue. As long as you are somewhat aware of where the drunks empty out of the bars it could hardly be more low key. I did a stretch where I didn't see one car for a few hours. Breakdowns, that's a concern..who wants to be wrenching a bike in the dark at 3am. Road hazards? 100s of night rides, I've never had a problem with unseen junk on the road or diving into some huge pothole.

Eccentric? That's an interesting thought. Turn it around...so you are an adult who has the experience, fitness, skill and gear to a marathon bike ride over night and watch the sun come up while in the saddle. Though it sound interesting, you do't do it because other peope regard it as weird of foolish..or perhaps they simply can't do it themselves. So, you choose not to experience it...and that's normal/healthy? Seems to me that's a worst diagnosis than being deemed eccentric.

I suppose the day will come when you can only ride a bike during certain hours in prescribed bike lanes. Until then, I'm riding my ride.