Sleeping under direct moonlight—especially during a full moon—is traditionally believed to cause physical or mental illness. Folklore warns of conditions such as fatigue, madness, blindness, or even spiritual possession resulting from prolonged lunar exposure during sleep. The belief often portrays moonlight as a subtle but dangerous force, capable of disrupting the body’s internal balance.
Historically, the superstition was rooted in pre-scientific medical systems that emphasized environmental influence on health. Moonlight was considered a cooling, damp force that could penetrate and alter bodily humors or invite spiritual contamination. Terms such as “moonstruck” and “moonblind” emerged from the idea that lunar exposure affected both physical and mental health.
