Psychosocial stress disrupts sleep, and the timing of stress relative to sleep affects dream content. When stress occurred before sleep, early-night dreams had higher threat intensity; when stress was anticipated after sleep, late-night dreams had higher threat intensity. Surprisingly, pre-sleep relaxation led to more negative early-night dreams, possibly due to a virtual-reality relaxation protocol. No difference was found in the incorporation of threat- and stress-related elements in dreams overall. The findings suggest that mental activity related to a stressor is reactivated in temporal proximity to the stressor, influencing dream emotionality and length.
Combining a wake-up-back-to-bed sleep protocol with a mnemonic technique and an odor cue during sleep failed to improve lucid dream induction. Only 2 of 16 male participants (12.5%) experienced a lucid dream in a single laboratory night, a lower success rate than the 50% achieved in the same group's prior study without odor. The authors conclude that odor-cueing does not appear to be a promising technique for inducing lucid dreams and discuss other methodological changes that may explain the reduced effectiveness.
Awakenings to collect dream reports impair subjective and objective sleep quality but do not affect sleep-associated memory consolidation in a word-picture association learning task. Memories of the learning task are successfully incorporated into dreams collected during the night, but not into morning dream reports. Incorporation into non-rapid eye movement sleep dreams, but not rapid eye movement sleep dreams, positively predicts memory performance the next morning. The findings suggest that awakenings are a suitable method for dream and memory studies, and that non-rapid eye movement sleep dreams may be more related to memory consolidation processes than rapid eye movement sleep dreams.