I got a (new) pet rat a few months ago. She's very young and fairly energetic.. at times. Problem is, she's incredibly thin. I've given her everything I can think of to make her gain weight (and she eats it quite readily). So far, it hasn't made a difference.
Also, she's either very energetic or sleeping. She sleeps a LOT. Like I'll put her on my bed and she'll run around for 5 minutes, then just lay.. anywhere, and fall asleep. Doesn't matter what the time of day is.
Is she sick? She doesn't SEEM sick. No sneezing or nose discharge. Her heartbeat and breathing seem regular. If she wasn't so skinny I wouldn't worry.