Storms & Nisbett, 1970: Attributing arousal to inert pill decreased time to fall asleep among insomniacs
Insomniacs were given a pill to take at bedtime over two nights. The pill was inert but participants were told either that it would increase physiological arousal (e.g., heart rate, temperature), encouraging them to attribute arousal to the pill rather than to other emotional sources, or that it would decrease it arousal. As compared to participants told the pill would decrease arousal, participants told that the pill would increase arousal reported falling asleep more quickly over the two nights. A no-pill control group fell in between the two pill groups.