Does training increase NREM dream recall? A pilot study

Abstract

The percentages of successful dream recall vary depending on whether the participants were awakened from REM sleep (about 80% recall) or NREM sleep (about 50% recall). The question as to whether this difference is explained by less dreaming during NREM sleep or sleep state-dependent memory processes cannot answered easily. The present pilot study was designed to test whether high recallers can increase their NREM dream recall to figures equal to those obtained from REM awakenings. The participants were awakened during NREM on three non-consecutive nights while training in dream recall by keeping a dream diary. Even though the study’s goal was not achieved, the findings support the hypothesis that dreaming is always present during NREM sleep and that reduced NREM recall percentages are explained by sleep stage-dependent recall processes. Future research should focus on these sleep stage-dependent recall processes and correlate possible interindividual differences with their differences in dream recall.