Effects of the 1989 San Francisco earthquake on frequency and content of nightmares.

In a systematic evaluation of the effects of a natural disaster on nightmares, nightmare frequency was found to be about twice as high among 92 San Francisco Bay area college students as among 97 control subjects in Tucson, Arizona, after the 1989 Loma Prieta earthquake. Subjects in California had not only more nightmares in general but substantially more nightmares about earthquakes. Over a 3-week period, about 40% of those in the San Francisco Bay area reported one or more nightmares about an earthquake, as compared with only 5% of those in Arizona. However, nightmares about earthquakes were not more emotionally intense than other nightmares. These findings support the long-held view that the experience of a potentially traumatic event can result in more frequent nightmares, particularly about the event itself, but contradict the common opinion that nightmares about such events are unusually intense.