Indian Yoga is supposed to honor the day/night cycle since the biological clock of the human bodies is synchronized with the light. And for the maximum benefit yoga is traditionally done early mornings or evenings (sunrise/sunset).
I'm not sure if midnight is the right time to meditate or sink into a deeply spiritual practice as yoga.

I don't think I could stay awake either! But I can see how it would be a good social gathering for night owls and a wonderful alternative to bars and clubs.

Practicing yoga ( I mean asana and pranayama - not the other parts) at non physiological clock cycles is harmful for the body. Medically there is no question on this.

Yoga shoule be practiced only early in the morning or at dusk.Midnight yoga can be harmfull to the body

Midnight Yoga! Sounds really interesting. I believe the time one practices should be a personal choice based on when you feel inspired to do so. The benefits derived are essentially based on your beliefs about it.

While being up at night may not be the best for the body, many people choose to work shift work (evenings and overnights) because it opens up your days to other opportunities. I could see where offering midnight yoga to this population would be a benefit -- if you have to be up all night anyway, starting it out with yoga is better than caffeine.

I have worked overnights for many years and don't have any midnight yoga classes to take in my area, but I always get in a few minutes of asana and pranayama before work.