Restrict posting hours

I hope someone can help me, I’ve been looking for a plugin that restrincts posting hours.

I have a couple of pleople writing in my blog, and I really like how they write, but I can’t make them understand that posting at 2am is of no use to the page.

So I need to make the posting option unavailable from.. lets say 11pm to 6am.

Does anybody know if this is possible and if there exists a plugin?

Thanks!

Chofas