Do dreams really guard sleep? Evidence for and against Freud's theory of the basic function of dreaming

摘要

A series of studies investigating dream reports after nighttime awakenings with or without prior arousal during sleep allows testing this conjecture. In the first one (Conduit et al., 1997), young adult subjects were awakened after simultaneous light and tone stimulation just below the waking threshold, and mentation reports were compared to those elicited from control awakenings without stimulation. Results showed significantly more dream reports after sleep stimulation than without (83% vs. 40%). More precisely, a significant increase of dream reports under stimulation condition was found for non-rapid eye movement (NREM) sleep stage 2 (72% vs. 17%), but not for rapid eye movement (REM) sleep (100% vs. 84%)1. The NREM sleep finding was replicated with tone stimulation (46% vs. 9%; Fedyszyn and Conduit, 2007); by contrast, arousal during REM sleep was not associated with increased dreaming in subsequent studies (Fedyszyn and Conduit, 2007; Stuart and Conduit, 2009). It thus can be concluded that arousal during NREM sleep, not REM sleep, is associated with increased dreaming, which is a major argument supporting conjecture #1 (regarding NREM sleep only).