Joseph De Koninck

Total sleep deprivation and novelty processing: implications for frontal lobe functioning.

OBJECTIVE Mounting evidence suggests that the frontal lobes are particularly vulnerable to total sleep deprivation (TSD). Detection of novelty involves the frontal lobes. The presentation of rare, novel stimuli elicits an event-related potential (novel P3), which maximizes over anterior regions of the scalp. We hypothesized that TSD would impair novelty detection, resulting in a smaller novel P3 over the frontal region, with a topographic shift toward posterior areas. METHODS An auditory novelty oddball task was administered to a TSD group after 36 h of waking and again following recovery sleep, and to a control group after 12 h of waking. EEG was recorded from Fz, Cz and Pz. RESULTS A large anterior P3 was elicited in the control group. In the TSD group, this novel P3 was smaller at Fz. A later novel positivity appeared in parietal areas. The novel P3 returned to baseline levels and the late novel P3 was difficult to observe following recovery sleep. CONCLUSIONS TSD appears to compromise the usual automatic detection of novelty probably due to frontal deactivation. Participants may compensate by relying on posterior brain mechanisms involving active memory comparison. The late novel P3 component may also reflect a secondary effortful attempt to encode and to categorize novel stimuli. SIGNIFICANCE This study suggests that TSD may compromise cognitive functioning in different regions of the brain. The detection of novelty, probably mediated by the frontal lobes, is particularly at risk.

Trait anxiety and sleep-onset insomnia: Evaluation of treatment using anxiety management training

OBJECTIVES This study was initially designed to test the notion that generalized anxiety is a predominant factor in the maintenance of psychologically determined sleep-onset insomnia and that a trait anxiety reducing technique can provide significant therapeutic gains. METHODS Twenty participants (age 19-63) with moderate to severe sleep-onset chronic insomnia were first asked to monitor their sleep-onset latency (SOL) for a 3-week baseline period at home using a SOL clock device. Then, 10 received anxiety management training (AMT) for 9 weeks, while the remaining 10 were trained in the use of progressive relaxation (PR). All participants were measured before and after therapy using sleep laboratory recordings (three nights each), the Spielberger Trait Anxiety Inventory and the Beck Depression Inventory. Daily home sleep-onset measures with the SOL clock device were also taken during therapy. RESULTS There was no change in SOL over the 3-week baseline period. However, both groups experienced a significant improvement in SOL from pretreatment (end of baseline) to posttreatment periods. In the laboratory, both groups experienced a reduction in Stage 1 sleep as well as an increase in slow wave sleep (SWS) and sleep satisfaction. On the personality measures, both groups experienced a significant reduction in trait anxiety and a decrease in depression. Overall, there was no indication that one of the therapies was significantly better than the other in effecting changes. CONCLUSION These results suggest that both PR and AMT are efficient therapies for sleep onset insomnia and overall sleep quality. Improvements in the application of the AMT technique are proposed to maximize its usefulness.

Temporal references in dreams and autobiographical memory

In an attempt to determine whether temporal references identified in dreams follow the same temporal distributions as those documented for autobiographical memories, 28 younger women (18–35 years of age) and 30 older women (60–77 years of age) kept a home dream diary for 1 week and then slept 1 night in the laboratory for rapid eye movement sleep dream collection. The following morning, they identified temporal references in their dreams and produced a sample of autobiographical memories using the semantic cuing method. For both groups, there was a linear decrease in temporal references identified in dreams and autobiographical memories with increased remoteness for the last 30 years. As predicted, for the older group, there were similar cubic trends reflecting a disproportionately higher number of both temporal references identified in dreams and autobiographical memories from adolescence/ early adulthood compared with adulthood and childhood. The results support the notion of continuity between waking and dreaming memory processes.

Imagery Rehearsal Therapy for Frequent Nightmares in Children

This study examined the applicability of imagery rehearsal therapy (IRT) to children with frequent nightmares. Eleven boys and 9 girls aged 9 to 11, with moderate to severe primary nightmares (1 or more per week for 6 months) and without posttraumatic stress disorder, were randomly divided into an imagery rehearsal treatment group (n = 9) or a waiting-list (n = 11) group. ANCOVA with repeated measures revealed that, following a baseline period, IRT reduced the frequency of nightmares (p < .04; η2 = 0.22) in the treated group compared to the waiting-list group. This reduction was maintained over a 9-month follow-up. The effects of IRT on post-nightmare state distress could not be assessed due to low nightmare incidences. However, retrospective trait nightmare distress was not significantly reduced. Future research is needed to validate this simple approach for nightmare reduction and to evaluate its potential for the reduction of the associated nightmare distress.

Presleep Suggestion Related to a Phobic Object: Successful Manipulation of Reported Dream Affect

Twenty-four female subjects with a strong dislike of snakes slept for four nonconsecutive nights in the laboratory. They were divided into four groups of six, each group receiving a different presleep suggestion on Nights 3 and 4. On Nights 2, 3, and 4, before sleep, the subjects saw but did not have to touch a live snake and their dreams were collected for each REM period. The results showed that, when compared with the subjects who received the negative affect suggestions, subjects who received positive affect suggestions had significantly higher levels of positive emotions in their dreams, rated their own dreams as more pleasant, and had significantly lower levels of anxiety, sadness, and aggression. These results support the hypothesis that presleep suggestion can be an effective technique in influencing the affective dimension of the dream.

Nocturnal sleep, daytime sleepiness, and napping among women with significant emotional/behavioral premenstrual symptoms

The objective of this study is to examine daytime sleepiness and alertness and nap characteristics among women with significant emotional/behavioral premenstrual symptoms, and to determine their relationship with nocturnal sleep. Participants spent one night during the follicular phase and two nights during the late‐luteal phase, one of which occurred after a 40 min opportunity to nap, sleeping in the laboratory. Subjective measures of sleepiness and alertness were completed during the afternoon of each recording. Setting took place at the sleep laboratory at the University of Ottawa. A total number of participants were 10 women with significant and nine women with minimal emotional/behavioral premenstrual symptoms (mean age 26 years). The results were compared with the follicular phase, both groups of women had less slow wave sleep and more stage 2 sleep at night, as well as a higher daytime and nocturnal mean and maximum temperature during the late‐luteal phase. Women with significant symptoms were sleepier and less alert during the late‐luteal phase and had a higher overall mean nocturnal temperature compared with women with minimal symptoms. No significant differences were found between the two groups on nap characteristics and nocturnal sleep characteristics. Results show that women with more severe premenstrual symptoms are sleepier during the late‐luteal phase than women with minimal symptoms. The increased daytime sleepiness seems to be unrelated to nocturnal sleep or nap characteristics.

Working mothers versus homemakers: Do dreams reflect the changing roles of women?

In order to examine potential psychological changes arising from womens new social roles, 15 working and 15 nonworking mothers were asked to report dreams collected within a period of three weeks. In addition, they were administered the Jackson Research Personality Form. Two dreams from each subject were analyzed with selected scales which previous studies had shown to be sensitive to sex differences. On the personality inventory, working mothers were found to have higher social recognition and achievement motives. On the dream content measures, discriminant analyses showed that the two groups could be statistically differentiated on the basis of several scales. In accordance with the notion of continuity between waking and dreaming, working mothers experienced more unpleasant emotions, more male characters, and less residential dreams settings than homemakers. The latter group, surprisingly, had more overt hostility in its dreams. These results suggest that as the trend toward carrying the dual role of wage earner and homemaker is expanding, the gender differences typically observed in dreams content may decrease. They also suggest that the analysis of dream content may prove useful to study the strategies of women adapting to role changes.

Reappearance of EEG slow waves in extended sleep

The log of the amplitude of EEG waves during NREM sleep is a linear function of the log of their frequency. The slope of this function is reliable within individuals, is significantly less steep in elderly than in young subjects and, in both groups, becomes flatter across successive NREM periods. We interpret these results as consistent with the hypothesis that the function of NREM sleep is to reverse the effects of waking on the brain. According to this model the decreased steepness of slope in the elderly and in later NREM periods reflects the diminishing intensity of these processes. Whatever the correct interpretation, the within-subject consistency of slope values permits their empirical study as a function of experimental manipulations. In addition, the quantitative F-A function established here (A = c/Fb) sets constraints that may prove useful for physiologic models of EEG waves during sleep.

Stress and Coping in the Waking and Dreaming States During an Examination Period

Dream diaries were kept by 35 female undergraduates for two ten-day periods, one of preparation for midterm or final examinations, and an exam-free one. Research questions were whether the stress and negative emotions induced by preparing for exams were reflected in dreams and what types of coping were used both in the waking and dreaming states. There was no consistent impact of the stressful situation on dreams, in terms of incorporation and negative emotions. However, 22 dreamers had incorporation dreams. They reported significantly less active problem-solving strategies in waking than the ones who had no such dreams. While a significant negative correlation was found between harm/threat emotions in waking and negative emotions in dream imagery, a positive correlation was found between positive reappraisal in waking and active problem-solving in dreams. Findings are discussed from the perspective of Lazarus and Folkmans theory of adaptation to stress in waking life.

Vertical inversion of the visual field and REM sleep mentation.

The effects of the vertical inversion of the visual field on REM sleep mental activity were examined to explore the potential involvement of this activity in information processing. In a first experiment, four male subjects slept in the laboratory for two sessions of 6 consecutive nights: 2 adaptation nights, 2 nights of polysomnography and 2 nights of dream collection. During the days preceding Nights 3, 4, 5, 6 of each session, the subjects wore glasses which, during the second session, completely inverted (rotation of 180°) their visual field. In a second experiment with four other male subjects, the order of conditions was reversed and the experimental condition (visual inversion) was introduced twice. The data of the two experiments were combined. Overall, following visual inversion, there were significant increases in the proportion of dreams containing motor and visual difficulties (P<0.005), misfortunes (P<0.05) and dreamer confusion (P<0.05) and a decrease in dreamer participation (P<0.05). Only 4 of the 8 subjects experienced incorporations of the inverted visual field into their dreams and they tended to perform better on two of three tests of adaptation to the visual inversion. The observed changes in dreams are consistent with the notion of continuity between waking and dreaming since they appear to reflect the waking preoccupation and psychological state associated with visual inversion.