Many moons ago, on reasonably mixed and easy ground on the hill I've been overwhelmed by vertigo that's put me on all fours - also, I've sprinted up vertical pitches without a care in the world, when perhaps more caution would have been appropriate really.
I think the brain can play tricks on you.
Is there a way of 'centering the mind' on the hoof so you can accurately "read" the immediate environment safely?