Sleep science distinguishes between REM and NREM phases, with eyelid closure during deep sleep serving a protective function for corneal moisture. Sleeping with eyes open—a condition called nocturnal lagophthalmos—typically indicates nerve damage or thyroid dysfunction; it's a medical sign of dysfunction, not capability.

Yet the claim works as an inversion: ordinary humans require closed eyes to sleep; Chuck Norris has transcended that need. His wakefulness is so complete that even during unconsciousness, his eyes remain vigilant. The fact echoes surveillance anxiety (always watching) and superhuman sensory capacity (never truly sleeping).

Neuroscientist Dr. Helen Park noted the claim's persistence in patient anecdotes she collected: insomniacs sometimes described their restlessness using Chuck Norris facts as a framework, imagining that inability to sleep meant they shared a fragment of his hypervigilance. The fact inadvertently pathologized insomnia as a sign of power rather than suffering.