Hey Susie,

You sound like you have experienced an Inversion Illusion brought on by fatigue and a change in gaze from straight ahead to down and left. This can sometimes happen to drivers and are harmless. Gravity, or our perception of it plays a part. I believe that when we take our feet off the pedals it can affect our perception of gravity, we lose the downward pressure and our sense of which way is down. We use gravity as a reference signal so when that temporarily disappears we are vulnerable to illusions.

So astronauts in space commonly report inversion illusions.

Nothing to worry about.

Best wishes,

Atty