doug m wrote:

Also, have found in very dark conditions that equilibrium can be
affected and that I probably brace more than needed due to feeling that
I'm about to dump. Odd sensation.

This is a variation of the condition known as "kayak angst". It can occur
whenever you're in a situation where you lose the ability to distinguish the
horizon. That usually means flat water with fog, heavy overcast or darkness,
and no landmarks or objects in the water. Basically, without any reference
points, your inner ear goes haywire and you can't maintain balance.
Fortunately, all it takes is ripples in the water or another paddler within
sight to eliminate the problem.

--
Regards

Brian