The word for today is…
proprioception (noun) – The unconscious perception of movement and spatial orientation arising from stimuli within the body itself. (Why you don’t fall out of bed when asleep).
An explanation of how this sense works:
Our body knows how it is moving and where it is because of a sense called “proprioception”. It’s like a “sixth sense” that helps your body know where it is in the world and where all the parts of your body are in relation to each other.
When we are awake, this sixth sense stops us from walking into things or falling over.
You might think that it would switch off when we’re sleeping. But because our bodies still work while we’re sleeping, our sixth sense is still working too.
Source : The Free Dictionary
Etymology : 1906, from proprioceptor, from Latin proprius “own” + reception. Coined by English neurophysiologist C.S. Sherrington (1857-1952).