Why Does My Modem Blink Even When I’m Not Using The Internet?

Dear Lifehacker, My cable modem and router just keep flashing all night, even when I'm not doing anything on the internet. I know my power light is supposed to be on, but should the send/receive light is blinking even when all my computers are turned off? Am I using up data at all times? Help! Sincerely, Blinking Lights

via http://lifehacker.com/5979481/why-does-my-modem-blink-even-when-im-not-using-the-internet