Daydreams and nap dreams: Content comparisons.

Differences between nighttime REM and NREM dreams are well-established but only rarely are daytime REM and NREM nap dreams compared with each other or with daydreams. Fifty-one participants took daytime naps (with REM or NREM awakenings) and provided both waking daydream and nap dream reports. They also provided ratings of their bizarreness, sensory experience, and emotion intensity. Recall rates for REM (96%) and NREM (89%) naps were elevated compared to typical recall rates for nighttime dreams (80% and 43% respectively), suggesting an enhanced circadian influence. All attribute ratings were higher for REM than for NREM dreams, replicating findings for nighttime dreams. Compared with daydreams, NREM dreams had lower ratings for emotional intensity and sensory experience while REM dreams had higher ratings for bizarreness and sensory experience. Results support using daytime naps in dream research and suggest that there occurs selective enhancement and inhibition of specific dream attributes by REM, NREM and waking state mechanisms.