Desert hallucination, or "ragle": A first description by Stanislas d'Escayrac de Lauture (1826-1868)

Pierre Henri Stanislas d'Escayrac de Lauture (1826-1868), a French aristocrat, was primarily an explorer with a keen interest in geography, science, and languages. He traveled extensively in North Africa, where he experienced both mirages and hallucinatory phenomena, which he termed "ragle" after an Arabic word. These hallucinations likely stemmed from sleep deprivation, though other factors may have contributed. In a memoir presented to the French Academy of Sciences in 1855, d'Escayrac provided the first precise description of desert hallucinations, distinguishing them from the already known mirages. This article provides a summary of d'Escayrac's adventurous life, his observations on ragle, and a commentary on them in the context of current knowledge of sleep-related hallucinations, and other possible contributing factors.