My wife is 25 years old and recently I have noticed clock ticking like Sound coming from her head. This happens only when she changes positions of sleep for like 2 seconds and only when she is really asleep. If she is little bit conscious while changing her position of sleep, no sound comes. She is completely unaware of it as she is asleep. It's very disturbing as I can't sleep if I hear any weird sound of slightest frequency. It's not snoring, it's non vocal. Should I be worried?