It began as a whisper, a strange affliction barely noticed amid the chaos of World War I. A handful of cases in Europe, then a few more in the United States. By 1916, the medical community was beginning to realize that something was wrong. People were falling into a bizarre state of near-sleep, unable to wake up fully, unable to move normally. Some died within weeks, while others recovered, only to be left with permanent neurological damage. Then there were those who neither died nor recovered — they became statues, trapped in time. Between 1916 and 1928, a wave of this strange illness swept across the world, infecting an estimated one million people. It was called encephalitis lethargica, or sleeping sickness. The disease didn’t just put people to sleep — it locked them inside their own bodies. Some were frozen in place for decades, their minds still intact but unable to communicate or move. Others developed violent, uncontrollable movements, or suffered devastating psychotic episodes. The epidemic vanished as mysteriously as it arrived, leaving thousands of survivors in asylums, nursing homes, or trapped within their own unresponsive bodies. Doctors never determined exactly what caused it, and a century later we still don’t know. The forgotten plague remains one of medicine’s greatest mysteries — a disease without a known origin, a cure, or an explanation.