Auditory Awakening Thresholds in Rem and Nrem Sleep Stages

Abstract

Srrmmary.-The auditory awakening thresholds of the major electroencephalographically defined sleep stages were compared. A modification of the method of constant stimuli was used in an apparently successful attempt to minimize the incorporation of the experimental stimuli into the mental activity of the sleeper. A total of 319 experimental trials were distributed among seven human Ss who served for about six experimental nights each. The sequence and timing of experimental trials were counterbalanced to control for nights, habituation, amount of accumulated sleep, and amount of sleep since last awakening. The results showed approximately equal awakening thresholds during REM periods (the rapid eye movement stage of sleep) and stage 2 (low voltage EEG and 12 to 1 4 cps "sleep spindles"). Both these stages had lower awakening thresholds than delta sleep (large slow EEG waves). Awakening thresholds became lower with accumulated sleep, independent of sleep stage. There were no significant stage independent relationships between awakening threshold and time since last awakening or time since last body movement, although the latter were varied over a relatively narrow range which limits the generaliry of these findings. There was no stage independent relationship between heart rate and awakening threshold. The possible physiological determinants of the awakening response were discussed.During the past decade, much information has been gathered which compares psychological and physiological functioning in REM (rapid eye movement) and N R E M ( n o rapid eye movement) sleep stages; this information has recently been reviewed by Dement (1964). The present scudy aims to contribute to this body of information by comparing the sleep stages, as defined by Dement and Kleitman (1957), with respect to auditory awakening threshold. Since this study was begun, another report on the relationship becween sleep stages and awakening threshold has been published (Goodenough, Lewis, Shapiro, Jaret, & Sleser, 1965). The present scudy is nevertheless reported in detail because, not only does ic have corroborative value, but ic employs a different methodology which contributes further to a. clarification of sleep scageawakening threshold relacionships.

Infant Arousals During Mother-Infant Bed Sharing: Implications for Infant Sleep and Sudden Infant Death Syndrome Research

“…Together with previous evidence that arousal threshold is relatively high in the EEG delta range, [23][24][25] this supports the premise that infant arousability is comparatively diminished in stage 3-4. This also further legitimizes our primary interest in any changes in stage 3-4 associated with bed sharing, as might pertain to the hypothesized role of arousal deficiency in susceptibility to SIDS.…”

“…10,21,22 Arguably, this selective increase in quiet sleep might undermine infant arousability because arousal threshold has been shown to be high in the EEG delta range in human infants and adults as well as in rats. [23][24][25] That the majority of normal infants under 7 months of age fail to arouse in response to a hypoxic challenge in quiet sleep illustrates that infant arousability is attenuated in quiet sleep. 26 Furthermore, Schechtman et al 27 have provided specific evidence that enhanced quiet sleep (which is associated with EEG delta waves) may contribute to SIDS.…”

The Effect of Noise during Sleep on the Sleep Patterns of Different Age Groups

“…The sleep records of nights 3 and 4 were used as the base for the control condition to minimize the 'first night effect' of nights 1 and 2 and also any participation effects of night 5. Table I shows the number of awakenings and stage shifts for the three age groups for the four conditions; control nights (3)(4) , awakening nights (6-8) , shift nights (9-14), and recovery night (15). The number of awakenings during the awake condition was 8.9 as compared to only 6.3 during the shift condition and only 5.9 in the control condition.…”

Decreased Connectivity between the Thalamus and the Neocortex during Human Nonrapid Eye Movement Sleep

“…4 Such increases are associated with parallel changes in firing patterns of nonspecific thalamocortical neurons: in light sleep, nonspecific …”