Plenty of visual illusions night over water w/o horizon.

Heck, I've even maneuvered to avoid oncoming traffic that turned out to be a tower in the distance - 300' on a dark night w/NVGs can produce some interesting illusions as well.

This article seems to make it all about the sleep inertia, but in reality, it's a visual illusion. More susceptible with some sleep inertia? I don't know - maybe, possibly - but even wide awake and alert you're susceptible.