Did Thomas Willis describe narcolepsy?

Background: Narcolepsy is a disorder characterized by chronic daytime sleepiness, sudden sleep attacks and cataplexy. Westphal is often credited for first describing narcolepsy in 1877 and Gélineau for naming it in 1880. However, descriptions by Thomas Willis in the 17th century suggest that the disorder might have been recognized two centuries before. In this article, we explore the possibility of Willis (1621-1675), known as the founder of clinical neuroscience, having described narcolepsy in his works. Objective: Analyze Willis’ descriptions and identify any indications that he described narcolepsy. Compare Willis’ observations with modern understanding of narcolepsy. Methods: A group of sleep medicine specialists performed a review of Willis‘ publications, especially the English translation of "De Anima Brutorum" by Samuel Pordage. We compared Willi’s descriptions with the current definition of narcolepsy, altogether with a review of interpretations of Willis‘ work by later scholars, such as Lennox. Results: In one of his most influential works, "De Anima Brutorum," Willis describes a condition he named "continual somnolence" where patients presented with uncontrollable sleep episodes during activities such as talking, walking or eating. Willis described these individuals maintained normal functions between these episodes, aligning with narcolepsy’s intermittent sleep attacks . However, Willis did not mention symptoms suggestive of cataplexy, sleep paralysis, or hypnagogic hallucinations, raising the question if, indeed, he was describing the disease. He followed the description of his work with a case report of a man: “(...) afterwards growing aged, being given to idleness and drunkenness, became dull and stupid, and also Dropsical, with a great paunch, and his thighs and legs swelled (...) at length, though he was freed from the Dropsie, he was oppressed with so heavy a sleepiness, and that almost perpetually, that in what place soever he was, or what ever he was doing he would sleep”. Despite Willis’ descriptions being aligned with the current understanding of narcolepsy, his case report includes clinical signs that suggest the patient might have had other diagnoses. These alternative diagnoses include hepatic encephalopathy and cardiac insufficiency, which could explain "dropsie" (a term historically used to describe edema or swelling), obstructive and/or central sleep apnea syndrome. These conditions could present symptoms like those described by Willis, such as excessive daytime sleepiness, although with the rare occurrence of the “sleep attacks” described. Conclusion: It is possible that some of Willis‘ patients might have had narcolepsy; however, among some of the patients that inspired his descriptions, alternative diagnoses were probably present. These could include systemic diseases and other causes of hypersomnia, especially given the absence of detailed descriptions of cataplexy, sleep paralysis, and hypnagogic hallucinations.