Do dreams reflect a biological state?

The purpose of this study was to prospectively evaluate the hypothesis that dreams reflect biological states. Inpatients on a nonacute cardiology service were studied. Dream material was gathered by an independent interviewer using the Staged Interview Technique, a newly developed interview technique that limited bias. The outcome measures used were obtained at the time of cardiac catheterization. Different levels of severity of cardiac disease with these measures were interpreted as representing different biological states. The patients' dreams were evaluated for the predicted correlations of the number of dream references to death (men) and separation (women) with different levels of severity of heart disease. The severity of heart disease was evaluated with anatomical (coronary angiography) and physiological (ejection fraction) measures obtained at cardiac catheterization, each represented by a 6-point scale of increasing severity. There was no correlation of the number of dream references with the severity of abnormalities on coronary angiography. However, the number of dream references to death and separation correlated with the severity of cardiac dysfunction, as measured by the ejection fraction, which is a more sensitive parameter of disease severity. The data provided prospective support for the hypothesis by showing that dreams reflected a biological state, the ejection fraction. This suggested a possible biological "meaning" of dreams.