Mouse Dreaming?

Question
Hi there,
I have two fancy pet mice and I was wondering about this squeaking noise that I sometimes here when the girls are sleeping. Usually I hear it early morning or at night. It's best described as a constant squeaking chirp that continues until I wake her up. Is this a case of a mouse dreaming? Both of the girls are active little guys. They eat normally and they drink normally too. They have nice shiny coats and clear eyes, no signs of poryphin or anything in their eyes. It's not even close to the sound of a mouse with respiratory illness. (I had a pet rat pass on with this about 2 weeks ago and another mousie who caught it eventually a while ago) The noise happens while the girls are sleeping and it stops when I wake them up.  Thanks for taking the time to read and answer!
-Whitney

Answer
Dear Whitney,

Can you see the mice sleeping or do you assume they are, because they are in the nest? Mice often squeak in the nest because one is washing the other a little too vigorously. Some mice also chirp when they are happy.  

If they are definitely sleeping-- eyes closed, not moving-- and chirping, then unless it's like a cat which continues to purr until it is in a deep enough sleep to stop, you might be right. I've never observed a mouse chirp in her sleep, but maybe sometimes when I assume I'm hearing happy or washing mice, I'm hearing dreaming.  However, it seems sort of unlikely, since the main activity of a mouse besides eating is hiding from predators, and making noise while you sleep is a bad way to do that.

How cute!

Squeaks n giggles,

Natasha