An elderly gentleman was wakened at night by his wife, who was alarmed because he laughed so loudly and unrestrainedly in his sleep. He explained later that he had had the following dream: ‘I was lying in my bed; an acquaintance came in; I wanted to turn up the light, but could not do it. I tried again and again—in vain. Thereupon my wife got up out of bed to help me, but she could not manage it either; but because she was embarrassed before the gentleman at being in her négligé she finally gave it up and went back to bed again; all this was so comical that I had to laugh exceedingly at it. My wife said, “Why do you laugh, why do you laugh?” but I only went on laughing,—till I wakened.’ The following day he was very depressed and had a headache—‘From laughing so much that I was exhausted’, he thought.