The Relationship Between Dreams and Subsequent Morning Mood Using Self-Reports and Text Analysis

While material from waking life is often represented in dreams, it is less clear whether and how dreams impact waking life. Here, we assessed whether dream mood and content from home diaries predict subsequent waking mood using both subjective self-reports and an objective automated word detection approach. Subjective ratings of dream and morning mood were highly correlated within participants for both negative and positive valence, suggesting that dream mood persists into waking. Text analyses revealed similar relationships between affect words in dreams and morning mood. Moreover, dreams referencing death or the body were related to worse morning mood, as was first-person singular pronoun usage (e.g., "I"). Dreams referencing leisure or ingestion, or including first-person plural pronouns (e.g., "we"), were related to better morning mood. Together, these results suggest that subjective experiences during sleep, while often overlooked, may be an important contributor to waking mood.

Supplementary Information

The online version contains supplementary material available at 10.1007/s42761-021-00080-8.

Effects of sleep on positive, negative and neutral valenced story and image memory

During sleep, emotional memories are preferentially strengthened. However, most studies on sleep and emotional memory focus on comparing negative valence with neutral valence stimuli. This study compared the sleep‐dependent memory effects for stories and images, each comprising negative, neutral, and positive stimuli. It was hypothesized that a sleep effect would be seen for negatively and positively valenced stimuli. A novel story memory task (comprising three stories), and photographs from the Nencki Affective Picture database were presented for learning to 61 healthy adults (ages 18–25). They were tested for memory on the two tasks immediately, and then again after either a 2‐hr nap (n = 31; 17 women, 14 men) or 2‐hr wake period (n = 30; 13 women, 17 men). At second testing, the sleep condition had significantly better recall compared to the wake condition on both tasks. There was a relationship with valence only for the story task, with better performance for the sleep condition on the negatively and positively valenced texts, but not on the neutral text. There were no significant relationships between memory measures and sleep‐stage duration and EEG power variables. The story memory findings support the hypothesis that memory consolidation prioritizes emotional memory, whether positively or negatively valenced.

Understanding the Associations of Prenatal Androgen Exposure on Sleep Physiology, Circadian Proteins, Anthropometric Parameters, Hormonal Factors, Quality of Life, and Sex Among Healthy Young Adults: Protocol for an International, Multicenter Study

Background

The ratio of the second finger length to the fourth finger length (2D:4D ratio) is considered to be negatively correlated with prenatal androgen exposure (PAE) and positively correlated with prenatal estrogen. Coincidentally, various brain regions are sensitive to PAE, and their functions in adults may be influenced by the prenatal actions of sex hormones.

Objective

This study aims to assess the relationship between PAE (indicated by the 2D:4D ratio) and various physiological (sex hormone levels and sleep-wake parameters), psychological (mental health), and sexual parameters in healthy young adults.

Methods

This study consists of two phases. In phase 1, we will conduct a survey-based study and anthropometric assessments (including 2D:4D ratio and BMI) in healthy young adults. Using validated questionnaires, we will collect self-reported data on sleep quality, sexual function, sleep chronotype, anxiety, and depressive symptoms. In phase 2, a subsample of phase 1 will undergo polysomnography and physiological and genetic assessments. Sleep architecture data will be obtained using portable polysomnography. The levels of testosterone, estradiol, progesterone, luteinizing hormone, follicle-stimulating hormone, prolactin, melatonin, and circadian regulatory proteins (circadian locomotor output cycles kaput [CLOCK], timeless [TIM], and period [PER]) and the expression levels of some miRNAs will be measured using blood samples. The rest and activity cycle will be monitored using actigraphy for a 7-day period.

Results

In Poland, 720 participants were recruited for phase 1. Among these, 140 completed anthropometric measurements. In addition, 25 participants joined and completed phase 2 data collection. Recruitment from other sites will follow.

Conclusions

Findings from our study may help to better understand the plausible role of PAE in sleep physiology, mental health, and sexual quality of life in young adults.

International Registered Report Identifier (IRRID)

DERR1-10.2196/29199

Frontal Brain Activity and Subjective Arousal During Emotional Picture Viewing in Nightmare Sufferers

Nightmares are intensely negative dreams that awaken the dreamer. Frequent nightmares are thought to reflect an executive deficit in regulating arousal. Within a diathesis-stress framework, this arousal is specific to negative contexts, though a differential susceptibility framework predicts elevated arousal in response to both negative and positive contexts. The current study tested these predictions by assessing subjective arousal and changes in frontal oxyhemoglobin (oxyHB) concentrations during negative and positive picture-viewing in nightmare sufferers (NM) and control subjects (CTL). 27 NM and 27 CTL subjects aged 18–35 rated subjective arousal on a 1–9 scale following sequences of negative, neutral and positive images; changes in oxyHB were measured by Near-Infrared Spectroscopy (NIRS) using a 2 × 4 template on the frontal pole. Participants also completed the Highly Sensitive Person Scale, a trait marker for differential susceptibility; and completed a dream diary reporting negative and positive dream emotionality. The NM group had higher trait sensitivity, yet higher ratings of negative but not positive emotion in diary dreams. NM compared to CTL subjects reported higher subjective arousal in response to picture-viewing regardless of valence. Dysphoric dream distress, measured prospectively, was negatively associated with frontal activation when viewing negative pictures. Results suggest NM sufferers are highly sensitive to images regardless of valence according to subjective measures, and that there is a neural basis to level of trait and prospective nightmare distress. Future longitudinal or intervention studies should further explore positive emotion sensitivity and imagery in NM sufferers.

Testing the theory of Differential Susceptibility to nightmares: The interaction of Sensory Processing Sensitivity with the relationship of low mental wellbeing to nightmare frequency and nightmare distress

Propensity to have nightmares has been theorised in terms of diathesis-stress models, with this propensity being seen as negative or even pathological. In contrast, a recent model proposes that nightmare propensity is due to Differential Susceptibility to stimuli, where high susceptibility can be beneficial in positive environments but detrimental in negative environments. This susceptibility to stimuli is assessed as the biobehavioural trait Sensory Processing Sensitivity, which refers to a greater responsivity to internal and external stimuli, and an increased depth of cognitive and emotional processing. To test the Differential Susceptibility Framework for nightmares, 137 participants (females = 104, males = 33; mean age = 33.66 years), recruited from a student population and social media sites, were divided into high (n = 39), medium (n = 59) and low (n = 39) Sensory Processing Sensitivity categories based on their score on the Highly Sensitive Person Scale. Low mental wellbeing and the presence of minor psychiatric problems, measured by the General Health Questionnaire, was found to be significantly correlated with nightmare frequency for the high and medium SPS groups (rs = .29 and .28, respectively), but not for the low Sensory Processing Sensitivity group (r = .19). General Health Questionnaire score was also significantly correlated with trait nightmare distress, for the high Sensory Processing Sensitivity group only (r = .32). These findings in favour of the Differential Susceptibility Framework have aetiology and treatment implications for nightmares that differ from diathesis-stress models.

Gender Differences in the Dream Content of Children and Adolescents: The UK Library Study

Although gender differences in the dreams of adults have been studied extensively, large-scale studies in children and adolescents are scarce. The UK Library Study collected 1,995 most recent dreams of children and adolescents. Boys reported more physical aggression and fewer female characters in their dreams, whereas indoor settings were more prominent in girls’ dreams, results that are consistent with the findings in adults and the continuity hypothesis of dreaming. The study indicates that dream content analysis is a valuable tool for studying the inner world of children and adolescents because dreams reflect their waking life experiences, thoughts, and concerns. It would be informative to include measures of waking life aggression, frequency of social contacts, and leisure time activities to provide evidence for direct links between waking and dreaming.

Testing the Empathy Theory of Dreaming: The Relationships Between Dream Sharing and Trait and State Empathy

In general, dreams are a novel but realistic simulation of waking social life, with a mixture of characters, motivations, scenarios, and positive and negative emotions. We propose that the sharing of dreams has an empathic effect on the dreamer and on significant others who hear and engage with the telling of the dream. Study 1 tests three correlations that are predicted by the theory of dream sharing and empathy: that trait empathy will be correlated with frequency of telling dreams to others, with frequency of listening to others' dreams, and with trait attitude toward dreams (ATD) (for which higher scores indicate positive attitude). 160 participants completed online the Toronto Empathy Questionnaire and the Mannheim Dream Questionnaire. Pearson partial correlations were conducted, with age and sex partialled out. Trait empathy was found to be significantly associated with the frequency of listening to the dreams of others, frequency of telling one's own dreams to others, and attitude toward dreams. Study 2 tests the effects of discussing dreams on state empathy, using an adapted version of the Shen (2010) state empathy scale, for 27 pairs of dream sharers and discussers. Dream discussion followed the stages of the Ullman (1996) dream appreciation technique. State empathy of the dream discusser toward the dream sharer was found to increase significantly as a result of the dream discussion, with a medium effect size, whereas the dream sharer had a small decrease in empathy toward the discusser. A proposed mechanism for these associations and effects is taken from the robust findings in the literature that engagement with literary fiction can induce empathy toward others. We suggest that the dream acts as a piece of fiction that can be explored by the dreamer together with other people, and can thus induce empathy about the life circumstances of the dreamer. We discuss the speculation that the story-like characteristics of adult human dreams may have been selected for in human evolution, including in sexual selection, as part of the selection for emotional intelligence, empathy, and social bonding.

Incorporation of recent waking-life experiences in dreams correlates with frontal theta activity in REM sleep

Rapid eye movement (REM) sleep and its main oscillatory feature, frontal theta, have been related to the processing of recent emotional memories. As memories constitute much of the source material for our dreams, we explored the link between REM frontal theta and the memory sources of dreaming, so as to elucidate the brain activities behind the formation of dream content. Twenty participants were woken for dream reports in REM and slow wave sleep (SWS) while monitored using electroencephalography. Eighteen participants reported at least one REM dream and 14 at least one SWS dream, and they, and independent judges, subsequently compared their dream reports with log records of their previous daily experiences. The number of references to recent waking-life experiences in REM dreams was positively correlated with frontal theta activity in the REM sleep period. No such correlation was observed for older memories, nor for SWS dreams. The emotional intensity of recent waking-life experiences incorporated into dreams was higher than the emotional intensity of experiences that were not incorporated. These results suggest that the formation of wakefulness-related dream content is associated with REM theta activity, and accords with theories that dreaming reflects emotional memory processing taking place in REM sleep.

The nature of delayed dream incorporation ('dream-lag effect'): Personally significant events persist, but not major daily activities or concerns

Incorporation of details from waking life events into rapid eye movement (REM) sleep dreams has been found to be highest on the 2 nights after, and then 5–7 nights after, the event. These are termed, respectively, the day‐residue and dream‐lag effects. This study is the first to categorize types of waking life experiences and compare their incorporation into dreams across multiple successive nights. Thirty‐eight participants completed a daily diary each evening and a dream diary each morning for 14 days. In the daily diary, three categories of experiences were reported: major daily activities (MDAs), personally significant events (PSEs) and major concerns (MCs). After the 14‐day period each participant identified the correspondence between items in their daily diaries and subsequent dream reports. The day‐residue and dream‐lag effects were found for the incorporation of PSEs into dreams (effect sizes of .33 and .27, respectively), but only for participants (n = 19) who had a below‐median total number of correspondences between daily diary items and dream reports (termed “low‐incorporators” as opposed to “high‐incorporators”). Neither the day‐residue or dream‐lag effects were found for MDAs or MCs. This U‐shaped timescale of incorporation of events from daily life into dreams has been proposed to reflect REM sleep‐dependent memory consolidation, possibly related to emotional memory processing. This study had a larger sample size of dreams than any dream‐lag study hitherto with trained participants. Coupled with previous successful replications, there is thus substantial evidence supporting the dream‐lag effect and further explorations of its mechanism, including its neural underpinnings, are warranted.

Characteristics of the memory sources of dreams: A new version of the content-matching paradigm to take mundane and remote memories into account

Several studies have demonstrated that dream content is related to the waking life of the dreamer. However, the characteristics of the memory sources incorporated into dreams are still unclear. We designed a new protocol to investigate remote memories and memories of trivial experiences, both relatively unexplored in dream content until now. Upon awakening, for 7 days, participants identified the waking life elements (WLEs) related to their dream content and characterized them and their dream content on several scales to assess notably emotional valence. Thanks to this procedure, they could report WLEs from the whole lifespan, and mundane ones before they had been forgotten. Participants (N = 40, 14 males, age = 25.2 ± 7.6) reported 6.2 ± 2.0 dreams on average. For each participant, 83.4% ± 17.8 of the dream reports were related to one or more WLEs. Among all the WLEs incorporated into dreams dated by the participants (79.3 ± 19%), 40.2 ± 30% happened the day before the dream, 26.1 ± 26% the month before (the day before excluded), 15.8 ± 21% the year before the dream (the month before excluded), and 17.9 ± 24% happened more than one year before the dream. As could be expected from previous studies, the majority of the WLEs incorporated into dreams were scored as important by the dreamers. However, this was not true for incorporated WLEs dating from the day before the dream. In agreement with Freud's observations, the majority of the day residues were scored as mundane. Finally, for both positive and negative WLEs incorporated into dreams, the dreamt version of the WLE was rated as emotionally less intense than the original WLE. This result, showing that dreams tend to attenuate the emotional tone of waking-life memories towards a more neutral one, argues in favor of the emotional regulation hypothesis of dreaming.

The effects of improving sleep on mental health (OASIS): a randomised controlled trial with mediation analysis

BACKGROUND

Sleep difficulties might be a contributory causal factor in the occurrence of mental health problems. If this is true, improving sleep should benefit psychological health. We aimed to determine whether treating insomnia leads to a reduction in paranoia and hallucinations.

METHODS

We did this single-blind, randomised controlled trial (OASIS) at 26 UK universities. University students with insomnia were randomly assigned (1:1) with simple randomisation to receive digital cognitive behavioural therapy (CBT) for insomnia or usual care, and the research team were masked to the treatment. Online assessments took place at weeks 0, 3, 10 (end of therapy), and 22. The primary outcome measures were for insomnia, paranoia, and hallucinatory experiences. We did intention-to-treat analyses. The trial is registered with the ISRCTN registry, number ISRCTN61272251.

FINDINGS

Between March 5, 2015, and Feb 17, 2016, we randomly assigned 3755 participants to receive digital CBT for insomnia (n=1891) or usual practice (n=1864). Compared with usual practice, the sleep intervention at 10 weeks reduced insomnia (adjusted difference 4·78, 95% CI 4·29 to 5·26, Cohen's d=1·11; p<0·0001), paranoia (-2·22, -2·98 to -1·45, Cohen's d=0·19; p<0·0001), and hallucinations (-1·58, -1·98 to -1·18, Cohen's d=0·24; p<0·0001). Insomnia was a mediator of change in paranoia and hallucinations. No adverse events were reported.

INTERPRETATION

To our knowledge, this is the largest randomised controlled trial of a psychological intervention for a mental health problem. It provides strong evidence that insomnia is a causal factor in the occurrence of psychotic experiences and other mental health problems. Whether the results generalise beyond a student population requires testing. The treatment of disrupted sleep might require a higher priority in mental health provision.

FUNDING

Wellcome Trust.

Assessing the dream-lag effect for REM and NREM stage 2 dreams

This study investigates evidence, from dream reports, for memory consolidation during sleep. It is well-known that events and memories from waking life can be incorporated into dreams. These incorporations can be a literal replication of what occurred in waking life, or, more often, they can be partial or indirect. Two types of temporal relationship have been found to characterize the time of occurrence of a daytime event and the reappearance or incorporation of its features in a dream. These temporal relationships are referred to as the day-residue or immediate incorporation effect, where there is the reappearance of features from events occurring on the immediately preceding day, and the dream-lag effect, where there is the reappearance of features from events occurring 5–7 days prior to the dream. Previous work on the dream-lag effect has used spontaneous home recalled dream reports, which can be from Rapid Eye Movement Sleep (REM) and from non-Rapid Eye Movement Sleep (NREM). This study addresses whether the dream-lag effect occurs only for REM sleep dreams, or for both REM and NREM stage 2 (N2) dreams. 20 participants kept a daily diary for over a week before sleeping in the sleep laboratory for 2 nights. REM and N2 dreams collected in the laboratory were transcribed and each participant rated the level of correspondence between every dream report and every diary record. The dream-lag effect was found for REM but not N2 dreams. Further analysis indicated that this result was not due to N2 dream reports being shorter, in terms of number of words, than the REM dream reports. These results provide evidence for a 7-day sleep-dependent non-linear memory consolidation process that is specific to REM sleep, and accord with proposals for the importance of REM sleep to emotional memory consolidation.

Procedural and declarative memory task performance, and the memory consolidation function of sleep, in recent and abstinent ecstasy/MDMA users

Ecstasy/MDMA use has been associated with various memory deficits. This study assessed declarative and procedural memory in ecstasy/MDMA users. Participants were tested in two sessions, 24 h apart, so that the memory consolidation function of sleep on both types of memory could also be assessed. Groups were: drug-naive controls (n = 24); recent ecstasy/MDMA users, who had taken ecstasy/MDMA 2-3 days before the first testing session (n = 25), and abstinent users, who had not taken ecstasy/MDMA for at least 8 days before testing (n = 17). Procedural memory did not differ between groups, but greater lifetime consumption of ecstasy was associated with poorer procedural memory. Recent ecstasy/MDMA users who had taken other drugs (mainly cannabis) 48-24 h before testing exhibited poorer declarative memory than controls, but recent users who had not taken other drugs in this 48-24-h period did not differ from controls. Greater lifetime consumption of ecstasy, and of cocaine, were associated with greater deficits in declarative memory. These results suggest that procedural, as well as declarative, memory deficits are associated with the extent of past ecstasy use. However, ecstasy/MDMA did not affect the memory consolidation function of sleep for either the declarative or the procedural memory task.

Emotional content of dreams in obstructive sleep apnea hypopnea syndrome patients and sleepy snorers attending a sleep-disordered breathing clinic

STUDY OBJECTIVES

To assess prospectively the emotional content of dreams in individuals with the obstructive sleep apnea hypopnea syndrome (OSAHS) and sleepy snorers.

METHODS

Prospective observational study. Forty-seven patients with sleepiness and snoring attending a sleep-disordered breathing clinic, completed a morning diary concerning pleasantness/unpleasantness of their dreams for 10 days, and then had AHI assessed by a limited-channel home sleep study. Participants and groups: Sleepy snorers, AHI < 5: n = 12 (mean age = 51.00 years [SD 7.01], 7 males); AHI 5 -14.9, n = 14 (mean age = 49.71 y [9.73], 12 males); AHI ≥ 15, n = 21 (mean age = 56.33 [11.24], 16 males).

RESULTS

All groups reported similar numbers of dreams and nightmares during the diary period. The AHI ≥ 15 group were significantly higher on dream unpleasantness than were the sleepy snorers (p < 0.05); and when only males were analyzed, this difference was also significant (p = 0.01). As AHI increased across the 3 groups, there was a significant decrease in variability of dream emotions (Levene test for homogeneity of variance between the 3 groups, p = 0.018). Mean daytime anxiety and daytime depression were significantly correlated with mean dream unpleasantness and with mean number of nightmares over the diary period.

CONCLUSIONS

Patients with AHI ≥ 15 had more emotionally negative dreams than patients with AHI < 5. The variation in mean dream emotion decreased with increasing AHI, possibly because sleep fragmentation with increasing AHI results in fewer and shorter dreams, in which emotions are rarer.

The incidence of unpleasant dreams after sub-anaesthetic ketamine

RATIONALE

Ketamine is an N-methyl-D: -aspartate (NMDA) receptor antagonist with psychotogenic effects and for which there are diverse reports of whether pleasant or unpleasant dreams result during anaesthesia, post-operatively or after sub-anaesthetic use.

OBJECTIVE

To assess in healthy volunteers the incidence of unpleasant dreams over the three nights after receiving a sub-anaesthetic dose of ketamine, in comparison to placebo, and with retrospective home nightmare frequency as a covariate.

METHOD

Thirty healthy volunteers completed questionnaires about retrospective home dream recall and were then given either ketamine (n = 19, males = 9, mean age = 23.5 years; mean ketamine blood plasma = 175.29 ng/mL) or placebo (n = 11, males = 5, mean age = 25.4 years). Dream recall and pleasantness/unpleasantness of dream content were recorded by questionnaire at home for the three nights after infusion.

RESULTS

Ketamine resulted in significantly more mean dream unpleasantness relative to placebo and caused a threefold increase in the odds ratio for the incidence of an unpleasant dream. The number of dreams reported over the three nights did not differ between the groups. The incidence of unpleasant dreams after ketamine use was predicted by retrospectively assessed nightmare frequency at home.

CONCLUSIONS

Ketamine causes unpleasant dreams over the three post-administration nights. This may be evidence of a residual psychotogenic effect that is not found on standard self-report symptomatology measures or a result of disturbed sleep electrophysiology.

Evaluating the awakening criterion in the definition of nightmares: how certain are people in judging whether a nightmare woke them up?

There is debate about whether to include in the definition of nightmares a criterion that the imagery or emotions of the nightmare caused the person to wake up. This study investigates whether people believe that they can judge this cause of awakening. 42 participants recorded for 14 nights whether they had a dream, and decided for each dream whether it had or had not woken them. They then rated on a 5-point scale (where 1 = very certain and 5 = very uncertain) how certain they were in their decision of whether or not the dream woke them. Participants' mean certainty was high for decisions that the dream woke them (mean certainty = 1.60), and for very unpleasant dreams this mean certainty that the dream woke them was very high (mean certainty = 1.27). Dreams judged to have caused awakening were found to be more unpleasant than dreams judged not to have caused awakening. Although the inclusion of the awakening criterion did not increase the association of nightmare frequency with anxiety, there may be other advantages in the use of the awakening criterion.

The ability to self-tickle following Rapid Eye Movement sleep dreaming

Self-produced tactile stimulation usually feels less tickly--is perceptually attenuated--relative to the same stimulation produced externally. This is not true, however, for individuals with schizophrenia. Here, we investigate whether the lack of attenuation to self-produced stimuli seen in schizophrenia also occurs for normal participants following REM dreams. Fourteen participants were stimulated on their left palm with a tactile stimulation device which allowed the same stimulus to be generated by the participant or by the experimenter. The level of self-tickling attenuation did not differ between REM and non-REM sleep awakening conditions, where presence or absence of an accompanying dream was not controlled for. However, for the female participants, when awakening occurred from an REM sleep dream, self-stimulation ratings were higher than for external stimulation, whereas ratings after NREM sleep unaccompanied by a dream were lower for self-stimulation than for external stimulation. These results indicate deficits in self-monitoring and a confusion between self- and externally generated stimulation accompany REM dream formation.

The relationship of nightmare frequency and nightmare distress to well-being

Nightmares can be defined as very disturbing dreams, the events or emotions of which cause the dreamer to wake up. In contrast, unpleasant dreams can be defined in terms of a negative emotional rating of a dream, irrespective of whether or not the emotions or events of the dream woke the dreamer. This study addresses whether frequency of unpleasant dreams is a better index of low well-being than is frequency of nightmares. A total of 147 participants reported their nightmare frequency retrospectively and then kept a log of all dreams, including nightmares, for 2 weeks, and rated each dream for pleasantness/unpleasantness. Anxiety, depression, neuroticism, and acute stress were found to be associated with nightmare distress (ND) (the trait-like general level of distress in waking-life caused by having nightmares) and prospective frequency of unpleasant dreams, and less so with the mean emotional tone of all dreams, or retrospective or prospective nightmare frequency. Correlations between low well-being and retrospective nightmare frequency became insignificant when trait ND was controlled for, but correlations with prospective unpleasant dream frequency were maintained. The reporting of nightmares may thus be confounded and modulated by trait ND: such confounding does not occur for the reporting of unpleasant dreams in general. Thus there may be attributional components to deciding that one has been awoken by a dream, which can affect estimated nightmare frequency and its relationship with well-being. Underestimation of nightmare frequency by the retrospective questionnaire compared with logs was found to be a function of mean dream unpleasantness and ND.

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.

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.