Do ants sleep?

I'm curious: If I leave any manner of food on my outside table overnight you can guarantee that by the morning there is a steady march of ants trying to escort it, fragment by fragment, to their little ant houses. (ant houses, not out houses - they don't build little outdoor toilets - so far as I'm aware)

And yet if I leave food on the table in front of me like now(night time) there's not an ant to be seen. Do they sleep at night? It can't be because I'm here, ants aren't shy. They don't do little ant screams and run away when I come outside in the morning. Nothing interrupts their marching activities until I take the food source to the outdoor bin.

You know what I think? Ants are solar powered. They can only operate in sunlight. That explains why Australia has so many of them. There's no shortage of sunlight here and this country has more ants than anywhere I've ever been in my life.

I think this is an important issue that needs discussion. I may call Nova radio in the morning - they have lots of intelligent listeners.