Humans and cats both have certain muscles that are for precision, as well as what are called larger “anti-gravity muscles” like those that lift your legs. Those larger ones are activated by a neurochemical called serotonin. During REM sleep, the brain’s serotonin system is shut off, which means the anti-gravity muscles are shut off. What’s not switched off are these highly-tuned muscles in things like eyes and extremities—what for us would be fingers and toes, but for them it’s paws and whiskers. This kitten is in the state of sleep some people call “the sleep of the body,” because the body is totally relaxed except for these tips of things twitching, while the brain is active and dreaming.
Dr. Dodman has plenty more to tell us about the cat and kitten, at NatGeo Daily News. Link -Thanks, Marilyn!