wireless networking - What is the easiest way to turn off the wifi connection in my home at night?

Possible Duplicate:
How to disable internet access at night on the router?

I have teenagers who stay up all night and skype with their friends on their laptops.

Is there a way I can turn this off at a certain time every night without having to physically unplug my AT&T Gateway modem? I am not very computer savvy. Sorry if this sounds silly....