Contentment
There are few things more likely to induce contentment than being curled up in a warm flat on cold night with a soft-furred, sleeping puss against you, gently purring, paws twitching after dream mice. Until she starts so swiftly that she wakes herself and in true feline fashion digs in the claws so she can leap off.
This is why cat owners prefer jeans or something similar to denim to offer at least a bit of protection.
I do wonder how Pandora manages to wake herself like this. She reminds me of a former flatmate in my student days who would often fall asleep in front of the TV and start snoring, often so loudly he would actually snort like a pig with bronchiatis and wake himself up! Obviously this is not unique to humans.