The dream-lag effect: Selective processing of personally significant events during Rapid Eye Movement sleep, but not during Slow Wave Sleep.

Incorporation of details from waking life events into Rapid Eye Movement (REM) sleep dreams has been found to be highest on the night after, and then 5-7 nights after events (termed, respectively, the day-residue and dream-lag effects). In experiment 1, 44 participants kept a daily log for 10 days, reporting major daily activities (MDAs), personally significant events (PSEs), and major concerns (MCs). Dream reports were collected from REM and Slow Wave Sleep (SWS) in the laboratory, or from REM sleep at home. The dream-lag effect was found for the incorporation of PSEs into REM dreams collected at home, but not for MDAs or MCs. No dream-lag effect was found for SWS dreams, or for REM dreams collected in the lab after SWS awakenings earlier in the night. In experiment 2, the 44 participants recorded reports of their spontaneously recalled home dreams over the 10 nights following the instrumental awakenings night, which thus acted as a controlled stimulus with two salience levels, high (sleep lab) and low (home awakenings). The dream-lag effect was found for the incorporation into home dreams of references to the experience of being in the sleep laboratory, but only for participants who had reported concerns beforehand about being in the sleep laboratory. The delayed incorporation of events from daily life into dreams has been proposed to reflect REM sleep-dependent memory consolidation. However, an alternative emotion processing or emotional impact of events account, distinct from memory consolidation, is supported by the finding that SWS dreams do not evidence the dream-lag effect.

Cannabis and Ecstasy/ MDMA: empirical measures of creativity in recreational users.

This study investigated the associations between chronic cannabis and Ecstasy/MDMA use and one objective and two subjective measure of creativity. Fifteen abstinent Ecstasy users, 15 abstinent cannabis users, and 15 nondrug-user controls, completed three measures of creativity: the Consequences behavioral test of creativity, self-assessed performance on the Consequences test, and Gough's Trait Self-Report Creative Adjective Checklist. The Consequences test involved five scenarios where possible consequences had to be devised; scoring was conducted by the standard blind rating (by two independent judges) for "remoteness" and "rarity," and by a frequency and rarity of responses method. Cannabis users had significantly more "rare-creative" responses than controls (Tukey, p < 0.05); this effect remained significant with gender as a covariate. There were no significant differences between the groups on the number of standard scoring "remote-creative" ideas or for fluency of responses. On self-rated creativity, there was a significant ANOVA group difference (p < 0.05), with Ecstasy users tending to rate their answers as more creative than controls (Tukey comparison; p = 0.058, two-tailed). Ecstasy users did not differ from controls on the behavioral measures of creativity, although there was a borderline trend for self-assessment of greater creativity. Cannabis users produced significantly more "rare-creative" responses, but did not rate themselves as more creative.

Dynamic confidence during simulated clinical tasks.

OBJECTIVE: Doctors' confidence in their actions is important for clinical performance. While static confidence has been widely studied, no study has examined how confidence changes dynamically during clinical tasks. METHOD: The confidence of novice (n = 10) and experienced (n = 10) trainee anaesthetists was measured during two simulated anaesthetic crises, bradycardia (easy task) and failure to ventilate (difficult task). RESULTS: As expected, confidence was high in the novice and experienced groups in the easy task. What was surprising, however, was that confidence during the difficult task decreased for both groups, despite appropriate performance. CONCLUSIONS: Given that confidence affects performance, it is alarming that doctors who may be acting unsupervised should lose dynamic confidence so quickly. Training is needed to ensure that confidence does not decrease inappropriately during a correctly performed procedure. Whether time on task interacts with incorrect performance to produce further deficits in confidence should now be investigated.

Sleep deprivation and junior doctors' performance and confidence.

PURPOSE OF STUDY: To determine whether sleep deprivation affects not only junior doctors' performance in answering medical questions but whether their ability to judge their own performance is also affected by lack of sleep. METHODS: A questionnaire based follow up study in two district general hospitals of the Carmarthenshire NHS Trust. Eleven house officers and 15 senior house officers (SHOs) within the medical directorate participating in the on-call rota were recruited between July 1999 and May 2000. RESULTS: SHOs answered significantly more questions correctly (p=0.04) and were more confident than house officers when they were either correct or incorrect (p<0.001). Length of unbroken or continuous sleep is associated with more correct answers (p=0.03) and higher energy (p=0.09) and confidence (p=0.07) scores self rated by the profile of mood states. Length of continuous sleep was not related to the appropriateness of confidence, as measured by the "within-subject confidence-accuracy correlation" (p=0.919). CONCLUSIONS: SHOs performed better than house officers even allowing for sleep loss. Sleep deprivation had adverse effects on mood and performance but junior doctors can still monitor their performance and retain insight into their own ability when sleep deprived.

Effects of sleep loss on confidence-accuracy relationships for reasoning and eyewitness memory.

Participants (n = 48) deprived of sleep for 29-50 hr, in comparison with controls (n = 45), underestimated their performance on logical reasoning and Raven's matrices. Such caution may ameliorate adverse practical consequences of sleep loss. In contrast, although sleep loss participants were more suggestible on the Gudjonsson Suggestibility Scale (G. H. Gudjonsson, 1984, 1987), they maintained confidence in their suggestible responses and were inaccurate when responding with the highest rating of confidence. This indicates that the increased suggestibility is internalized and is due to a cognitive deficit rather than to compliance. Eyewitness confidence-accuracy correlations were low but usually significant and were lowest after 47-50 hr of sleep loss. Repetition of leading questions led to increases in confidence for suggestible responses (with no interaction with sleep loss) but not for nonsuggestible responses, indicating a problem for jurors' evaluations of practiced testimony.

Time of day effects in, and the relationship between, sleep quality and movement.

The study aimed to measure the effects of a 27-h 'day' sleep-wake regime on actigraphic and subjective sleep variables, and to examine the relationships between these variables. Nine subjects spent 30 days and nights in the laboratory. After sleeping 8 h for each of 8 nights, the subjects had an imposed 27-h 'day', for 18 'days', remaining in bed for 9 h on each sleep period. Sleep periods therefore started 3 h later each day, although subjects' circadian rhythms stayed entrained to 24 h, because subjects were not isolated from the natural light-dark cycle. Time asleep, subjective sleep efficiency and subjective sleep quality, but not movement during sleep, were found to be significantly affected by time of going to bed. There were significant decreases in movement during recovery sleeps following each of two episodes of 26 h sleep deprivation. Over the study there were significant within-subject correlations between subjective sleep quality and subjective sleep efficiency (rav = 0.65), movement during sleep and subjective sleep efficiency (rav = -0.48), and movement during sleep and subjective sleep quality (rav = -0.26). We conclude that sleep movement, despite its low within- and between-subjects variability, is nevertheless a statistically reliable, but weak, indicator of subjective sleep efficiency and quality.

Dreams, images and emotions associated with propofol anaesthesia.

One hundred and twelve patients scheduled for day case varicose vein surgery were randomly allocated to one of three groups: total intravenous anaesthesia with propofol, propofol induction followed by inhalational anaesthesia with nitrous oxide and isoflurane or thiopentone induction followed by inhalational anaesthesia with nitrous oxide and isoflurane. Assessments were made in the recovery room of the incidence of dreaming, the content of the dreams and the emotional status of the patients. The groups differed significantly in reporting that they had been dreaming: patients who underwent total intravenous anaesthesia reported the most dreaming and patients who received thiopentone the least. However, despite the large number of case reports of sexual imagery following propofol anaesthesia and despite the two groups who had received propofol experiencing significantly greater happiness upon recovery than the thiopentone group, there were no appreciable differences in the sexual content of the dreams. Each group had only a small number of dreams even remotely related to sex.