Do Flies Sleep?

I was eating dinner and some flies were troubling me. Then, I asked myself a question: Do flies ever sleep? I found my answers and here’s my summary below:

Flies do sleep and nap like all other living animals.
Like all other animals, when they’re asleep, their ability to respond decreases.
Flies will react in similar manner to other living things to the effects of caffeine where they had trouble sleeping after taking it.
Bush flies sleep on vegetation, tips of leaves and twigs.
Flies produce very similar sleeping habits with human.

Reference:
http://answers.google.com/answers/threadview?id=604566