Individual differences in mental activity at sleep onset.

[REM] period) mentation, CPIs, and thematic fantasy responses were collected from 32 young-adult Ss. In confirmation of recent findings by Foulkes and Vogel, dreamlike mental activity was found to occur with fairly substantial frequency at sleep onset, albeit with wide individual differences. Patterning of personality correlates with hypnagogic and nocturnal dream recall suggests that the former varies directly with waking ego-strength and adaptive flexibility, while the latter varies directly with indications of waking maladaptive symptomatology. A psychodynamic interpretation of these results is offered. Considerable evidence (e.g., Dement, 1965) has accumulated in recent years relating nocturnal dreaming to a particular phase of EEG sleep, ascending EEG Stage 1 accompanied by intermittent rapid eye movements (REMs). Periods of this stage of sleep recur in a cyclic fashion throughout the night. They are not normally observed at the onset of sleep, however, the first such period generally occurring only after an hour or more of non-REM sleep. Foulkes and Vogel (196S) have recently demonstrated the occurrence of dreamlike mentation at sleep onset in the absence of an ascending Stage 1 EEG or REMs. Although the content of such mentation may ultimately prove discriminable from content elicited during REM sleep, leaving undisturbed the association of REM sleep with a unique class of mental fantasy, these authors state that, by superficial appearance, it is not always easy to discriminate the sleep-onset dream from the REM-sleep dream. One of the most striking findings of the Foulkes and Vogel study was the extent of individual differences in the reporting of dreaming at sleep onset and in the association 1 Su-pport for the research herein reported has