What causes my lips to always be really red when I do not get enough sleep?

I'm more interested in the science behind it...I know there's nothing wrong with me and I'm healthy, otherwise. But if I get less than about 6 hours of sleep, my lips are red for a good part of the first bit of the day. Any suggestions on how this effects them? I'm a Caucasian, so it's more of a "looks like they are really chap" almost-lipstick red, which is disgusting looking for a guy.