Dreams of Canadians show more negative than positive themes, supporting the threat simulation theory. Gender differences in dreams mirror those in waking life, and the similarity of Canadian and American culture appears in dream imagery, consistent with the continuity hypothesis. Age-related patterns in dream content from adolescence to old age reflect waking developmental changes, also supporting continuity. The study used the dream diary method and Hall and Van de Castle content analysis on 600 dream reports from 150 young adults, plus additional samples of 75 females and 50 males across five age groups (12-17 to 65-85).
During sleep, the brain continues to process certain sounds that would normally trigger conscious awareness during wakefulness, as measured by the P3a event-related potential. A multi-feature paradigm presented standard and six types of deviant auditory stimuli during wakefulness, NREM, and REM sleep. Novel environmental sounds and white noise bursts elicited a P3a during wakefulness, replicating earlier findings, while other deviants (pitch, intensity, duration changes) did not. During N2 and REM sleep, the deviants that had elicited a P3a while awake continued to do so, though the sleeper did not awaken. This suggests processes leading to consciousness may remain active during sleep, potentially allowing detection of critical input without full arousal.