Sims 3: Why does this happen? :S?

When my sim is supposed to be sleeping, they sit up and look at their hand, it only happens for a few seconds but its annoying!! This has happened with a few of my sims when they're supposed to be sleeping. I thought it was to do with the medical beeper because the other sims that it happened with, are in the medical career, but this is justine keaton and she is in law enforcment so i dont know what is with it? Anyone help? ThankYou. :)