a way to force my dial-up modem to disconnect at a certain time?

Well, I'm on a single phone line dial-up connection for the summer and consequently, I can only download stuff during the night.

My stepdad and mom get up really early, around 6 AM and want to use the phone only to be greeted by a bunch of static and high pitched noises. Since they're too afraid of my computer to even touch it (Don't ask.) I have to wake up out of a deep sleep and disconnect it.

So, is there any way to do this automatically at a certain time? I browsed around in the connection options but couldn't find anything. I also Googled for a program to do this but that didn't yield anything either.

Any suggestions? (Can't get broadband here, sorry.)

Thanks!

Jam it back in, in the dark.