When in utero, babies spend 90% of their time asleep, during which most of that time is spent in REM sleep, or in other words they are dreaming. When you are dreaming, your brain paralyzes your skeletal muscle so that you don't act out your dreams, and this is called atonia. The thing is, atonia doesn't develop in humans until about a year after being born.
So basically, all the kicks and pushes that a mother feels when she is pregnant are not responses to the outside environment, they are side effects of the baby DREAMING without developed atonia.
When atonia fails in adulthood, it can have extreme consequences, ie you usually act very violent and can end up killing your spouse in your sleep. This is super rare. Sleep-walking-talking-sexting-eating is NOT you acting out your dreams as it occurs during non-REM sleep.
Sometimes atonia lingers around after you've already woken up, and you become consciously aware but unable to move a muscle - "sleep paralysis."
