Overnight, the sensors go quiet
The brain wakes up with a slightly out-of-date picture of where the body is.
Skin, fascia, joints and feet all stream sensory data continuously while you move through a day. In sleep, that traffic drops to near-idle. The internal model doesn't vanish — it just drifts out of date, the way a paused map app loses your position.
The first movements of the morning are not training. They are the body re-establishing a signal.