Mental activity at sleep onset.

Abstract

Experimental data, based upon a total of 212 hypnagogic awakenings contributed by 9 Ss, are presented on the incidence of reports of various forms of hypnagogic mentation and on the relationship of such reports to EEG activity. It was found that mental activity in some form or another was invariably reported throughout the hypnagogic period. Content reported was predominantly visual and lacking in affective intensity and it became increasingly hallucinatory and unamenable to voluntary control as EEG patterns shifted from an alpha EEG to a spindling EEG. Dreamlike reports very similar to REM reports (i.e., dramatic, hallucinatory episodes) were quite common during descending EEG Stages 1 and 2, and, surprisingly enough, also occurred with an alpha rhythm.

What subjective experiences determine the perception of falling asleep during sleep onset period?

“…Emotional intensity was low from the start and evinced little difference at any of the awakening junctures. These findings are consistent with previous studies that revealed significant change in sensory and thought process during sleep onset, while emotional experiences maintained a low intensity throughout (e.g., Foulkes & Vogel, 1965;Gibson et al, 1982;Hori, Hayashi, & Hibino, 1992;Hori, Hayashi, & Morikawa, 1991). This study's most significant finding is that control over the thinking process is the most prominent subjective experience that is associated with the judgment of having fallen asleep.…”

“…Behavioral indicators of sleep onset include: a decrease in sensory threshold, a cessation of responses to external stimuli (e.g., Anliker, 1966;Ogilvie & Simons, 1992;Ogilvie, Simons, Kuderian, MacDonald, & Rustenburg, 1991;Ogilvie & Wilkinson, 1984, 1988Ogilvie, Wilkinson, & Allison, 1989;Simon & Emmons, 1956), and a decrease in muscle strength (e.g., Jacobson, Kales, Lehmann, & Hoedemaker, 1964;Litchman, 1974) were also observed in the course of the sleep onset process. And, as regards the subjective experience of sleep onset, loss of awareness of environmen-tal stimuli and the loss of control over thought processes have both been reported (e.g., Foulkes & Vogel, 1965;Gibson, Perry, Redington, & Kamiya, 1982).…”

“…For example, Foulkes and Vogel (1965) collected 212 reports on the subjective experience of sleep onset from nine, young and healthy subjects, at four distinct junctures: continuous alpha EEG with rapid eye movements (REMs), discontinuous alpha EEG with slow eye movements (SEMs), descent into stage 1 sleep, and 0.5-2.5 min of stage 2 sleep. The aspects of subjective experience analyzed included sensory imagery, affect, thought control, and reality orientation.…”

Vigilance, alertness, or sustained attention: physiological basis and measurement

“…Also, self-reports of sleep may be altered in clinical situations: insomniacs were more likely to report themselves as awake when actually awoken from stage 2 sleep than controls (Moore et al, 1981). In terms of subjective experiences, arousals during this sleep onset period can produce self-reports of sensory experiences that would appear to represent dreaming (Foulkes and Vogel, 1965;Hori, 1994).…”

A methodological study of the effect of experimentally induced demand characteristics in research on nocturnal dreams.

“…A continuity has also been established between immediate pre-sleep, and sleep onset mentation that was to a certain extent co-existent with waking fantasy, as determined by the T.A.T. (Foulkes and Vogel, 1965;Vogel et al, 1966;Foulkes 1966;Vogel et al, 1972). Wood (1962) found that social isolation for a period of one day affected the content of his subjects' dreams recorded that night.…”