The Sleep That Lasted Decades: The Forgotten Plague of 1917

2026-07-02 · Strange Mass Events · 8 min read

In the winter of 1916, with the First World War grinding into its third year, physicians across Europe began seeing patients whose chief complaint fit no disease in the textbooks. The patients were sleepy. Not tired, not merely worn down by rationing and bad news, but overwhelmingly, irresistibly sleepy. A man would sit down to a meal and fall asleep with the fork halfway to his mouth. Some sank into a stupor from which they could barely be roused and slept for days or weeks on end. A few slipped into a coma and never woke again. Others suffered the exact reverse and could not sleep at all, lying awake night after night in a torment of insomnia.

In Vienna, the neurologist Constantin von Economo studied a series of these patients, concluded that he was looking at something genuinely new, and in 1917 gave it a name: encephalitis lethargica, an inflammation of the brain that brought sleep. The name stuck, and it has never been replaced.

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