Auditory inhibition of rapid eye movements and dream recall from REM sleep.

STUDY

OBJECTIVES

There is debate in dream research as to whether ponto-geniculo-occipital (PGO) waves or cortical arousal during sleep underlie the biological mechanisms of dreaming. This study comprised 2 experiments. As eye movements (EMs) are currently considered the best noninvasive indicator of PGO burst activity in humans, the aim of the first experiment was to investigate the effect of low-intensity repeated auditory stimulation on EMs (and inferred PGO burst activity) during REM sleep. It was predicted that such auditory stimuli during REM sleep would have a suppressive effect on EMs. The aim of the second experiment was to examine the effects of this auditory stimulation on subsequent dream reporting on awakening.

DESIGN

Repeated measures design with counterbalanced order of experimental and control conditions across participants.

SETTING

Sleep laboratory based polysomnography (PSG)

PARTICIPANTS

Experiment 1 : 5 males and 10 females aged 18-35 years (M = 20.8, SD = 5.4). Experiment 2 : 7 males and 13 females aged 18-35 years (M = 23.3, SD = 5.5).

INTERVENTIONS: Below-waking threshold tone presentations during REM sleep compared to control REM sleep conditions without tone presentations.

MEASUREMENTS AND

RESULTS

PSG records were manually scored for sleep stages, EEG arousals, and EMs. Auditory stimulation during REM sleep was related to: (a) an increase in EEG arousal, (b) a decrease in the amplitude and frequency of EMs, and (c) a decrease in the frequency of visual imagery reports on awakening.

CONCLUSIONS

The results of this study provide phenomenological support for PGO-based theories of dream reporting on awakening from sleep in humans.