In the summer of 1942, Lawrence LeShan of The College of William & Mary in Williamsburg, Virginia, stood in the darkness of a cabin in an upstate New York camp where a row of young boys lay sleeping. He intoned a single phrase, over and over: "My fingernails taste terribly bitter. My fingernails taste terribly bitter..." Anyone happening upon the scene might have thought LeShan had gone mad, but he had not. The professor was conducting a sleep-learning experiment.
All the boys had been diagnosed as chronic nail biters, and LeShan wanted to find out if nocturnal exposure to a negative suggestion could cure them. Initially he used a phonograph to faithfully repeat the phrase 300 times a night as the boys lay sleeping. One month into the experiment, a nurse discreetly checked their nails during a routine medical examination. One boy seemed to have kicked the habit. LeShan remarked that skin of a healthy texture had replaced the "coarse wrinkled skin of the habitual biter".
Then, five weeks into the investigation, disaster struck. The phonograph broke. Faced with having to abandon the experiment, LeShan began standing in the darkness and delivering the suggestion himself. Surprisingly, direct delivery had greater effect. Within two weeks, seven more boys had healthy nails. LeShan speculated that this was because his voice was clearer than the phonograph. Another possibility would be that his midnight confessions thoroughly spooked the children. "If I stop biting my nails," they probably thought, "the strange man will go away."
By the end of the summer, Leshan found that 40 per cent of the boys had kicked the habit, and concluded that the sleep-learning effect seemed to be real. Other researchers later disputed this. In a 1956 experiment at Santa Monica College in California, William Emmons and Charles Simon used an electroencephalograph to measure the brain activity of subjects, making sure they were fully asleep before playing a message. Under these conditions, the sleep-learning effect disappeared.
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