Fast sleep spindle density during NREM sleep is positively correlated with dream recall, especially bad dreams and the length of REM dream reports. In 53 healthy adults, fast spindles were most robustly linked to bad dream recall and the number of words in REM dream narratives. The associations varied by sleep cycle: bad dream recall correlated with spindles in cycles 2 and 3, while word count correlated with cycles 1, 4, and 5. Slow spindle density showed an opposite pattern of correlations.
People who habitually recall few dreams performed worse on a visuomotor task (mirror tracing) before sleep but showed greater overnight improvement than those who recall many dreams. The improvement in low recallers was linked to Stage 2 sleep rather than rapid eye movement sleep. The findings suggest that dreaming relates to visuomotor processes and that different levels of visuomotor skill engage distinct sleep-related consolidation mechanisms.