references. This may be related to the large decrease in familiar settings in the post-medication dreams. Although Domhoff (1996) does not list a high percentage of elements from the past as an indicator of psychopathology, he does mention that people suffering post-traumatic stress disorder (PTSD), a type of anxiety disorder, tend to have dreams in which distressing events are relived again and again. It may be that other anxiety disorders invoke a similar response in which the dreamer has a tendency to dwell on past events, which merits further research.
A final observation is that the results of this study provide support for Hartmann's (1984) biological model of the effects of drugs on dreams. An early study which focused mainly on long-term sleep patterns found little change in dream content associated with psychotropic drug administration (Hartmann & Cravens, 1974), but a later study conducted in Hartmann's laboratory indicated that increased levels of dopamine resulted in more vivid, nightmarish dreams (Hartmann, Russ, Oldfield, Falke, & Skoff, 1980). Based on his own research and the literature on drugs and nightmares, Hartmann (1984) proposed that drugs that increase the neurotransmitters dopamine or acetylcholine, or decrease norepinephrine or serotonin, produce nightmares and more vivid and bizarre dreams.
Drugs that have the opposite effects would decrease the incidence of disturbing dreams. The dreamer in this study was taking a serotonin reuptake inhibitor, which served to increase the effects of serotonin. According to the biological model, with the onset of medication the dreamer should have experienced a decrease in nightmares, or, in Hall and Van de Castle's terms, lower aggression, negative emotions, and other unpleasant factors. This was, in fact, the case.
The emphasis on statistically significant differences without regard to effect sizes slowed progress in the study of dream content by creating unnecessary polarities and focusing energy on methodological arguments. The introduction of effect sizes into the study of dream content makes it possible to suggest that the controversy over home and laboratory collected dream reports never should have happened. The emphasis in dream content studies henceforth should be on effect sizes and large samples. Then future dream researchers could focus on testing new ideas using dream reports collected either at home or in the sleep laboratory.