What are sleep-deprived visual hallucinations like?

Sleep deprivation: If deprived of sleep long enough, most people will experience misperceptions of visual reality (illusions) or actual hallucinations (perceptions without actual stimuli). Some think these are hypnogogic hallucinations brought on by microsleeps. It's very individual, but you might have flickering lights, shimmering edges of things, or a sense of the floor being covered by water. Best to get rest!