Healthy Good Sleepers Research Articles

States of consciousness and interoceptive hypersensibility: A study in patients with insomnia disorder.

This exploratory study aimed to investigate the relationship between interoceptive sensibility and quality of consciousness in individuals with insomnia disorder, in order to understand how the modulation of internal states may contribute to modifying the experience of consciousness during sleep difficulties. A total of 37 patients with insomnia disorder (mean age = 46.05 ± 18.16) and 41 healthy good sleepers (mean age = 50.2 ± 12.99) underwent a psychometric sleep and interoceptive sensibility assessment, using Insomnia Severity Index (ISI), Pittsburgh Sleep Quality Index (PSQI), and Multidimensional Assessment of Interoceptive Awareness (MAIA). Moreover, patients with insomnia disorder also completed a quality of consciousness evaluation, using the Phenomenology of Consciousness Inventory (PCI). Patients with insomnia disorder exhibited heightened interoceptive sensibility, particularly in noticing body sensations (p < 0.0001) and emotional awareness (p = 0.032), along with diminished abilities in attention regulation (p = 0.040), not-worrying (p = 0.001), and trusting (p = 0.002). Furthermore, correlations between interoceptive sensibility and multiple aspects of the consciousness state during the insomnia night were identified. Specifically, higher emotional awareness was linked to a 2.49-fold increase in the likelihood of subjectively experiencing altered consciousness states during insomnia. The study sheds light on the relationship between interoceptive sensibility and the subjective state of consciousness during insomnia, emphasising the importance of exploring and considering interoception as part of the therapeutic process for insomnia disorder. Given the exploratory nature of the study and the increased risk of type-I error from numerous correlations, the results should be interpreted with caution. Further research is needed to validate and confirm their robustness.

Ultradian sleep cycles: Frequency, duration, and associations with individual and environmental factors—A retrospective study

ObjectiveSleep varies between individuals in response to sleep-wake history and various environmental factors, including light and noise. Here we report on the intranight variation of the ultradian nonrapid eye movement-rapid eye movement (NREM-REM) sleep cycle in 369 participants who have contributed to different laboratory studies from 1994 to 2020 at the Centre for Chronobiology, Basel, Switzerland. ResultsWe observed a large interindividual variability in sleep cycle duration, including NREM and REM sleep episodes in healthy participants who were given an 8-hour sleep opportunity at habitual bedtime in controlled laboratory settings. The median sleep cycle duration was 96 minutes out of 6064 polysomnographically-recorded cycles. The number and duration of cycles were not normally distributed, and the distribution became narrower for NREM sleep and wider for REM sleep later in the night. The first cycle was consistently shorter than subsequent cycles, and moderate presleep light or nocturnal noise exposure had no significant effects on ultradian sleep cycle duration. Age and sex significantly affected NREM and REM sleep duration, with older individuals having longer NREM and shorter REM sleep particularly in the end of the night, and females having longer NREM sleep episodes. High sleep pressure (ie, sleep deprivation) and low sleep pressure (ie, multiple naps) altered ultradian sleep cycles, with high sleep pressure leading to longer NREM sleep in the first cycle, and low sleep pressure leading to longer REM sleep episodes. Positive correlations were observed between N2 and NREM duration, and between N1 and REM duration. Weak intrasleep REM sleep homeostasis was also evident in our data set. ConclusionsWe conclude that ultradian sleep cycles are endogenous biological rhythms modulated by age, sex, and sleep homeostasis, but not directly responsive to (moderate levels of) environmental cues in healthy good sleepers.

Genetic risk for insomnia is associated with objective sleep measures in young and healthy good sleepers

Insomnia disorder (ID) is the second most common neuropsychiatric disorder. Its socioeconomic burden is enormous while diagnosis and treatment are difficult. A novel approach that reveals associations between insomnia genetic propensity and sleep phenotypes in youth may help understand the core of the disease isolated from comorbidities and pave the way for new treatments. We obtained quantitative nocturnal sleep electroencephalogram (EEG) features in 456 participants (18-31y, 49 women). Sleep EEG was recorded during a baseline night following at least 7 days of regular sleep times. We then assessed daytime sleep onset latency in a subsample of N = 359 men exposed to manipulations affecting sleep pressure. We sampled saliva or blood for polygenic risk score (PRS) determination. The PRS for ID was computed based on genome-wide common single nucleotide polymorphism assessments. Participants also completed a battery of behavioral and cognitive tests. The analyses revealed that the PRS for ID was negatively associated with cumulated EEG power in the delta (0.5-4 Hz) and theta (4-8 Hz) bands across rapid eye movement (REM) and non-REM sleep (p ≤ .0026; β ≥ −0.13) controlling for age, sex and BMI. The PRS for ID was also negatively associated with daytime likelihood of falling asleep (β = −0.19, p = .0009). Other explorations for associations with non-baseline-nights, cognitive measures, and mood did not yield significant results. These results propose that the need or the ability to fall asleep and to generate slow brain activity during sleep may constitute the core sleep-related risk factors for developing ID.

Abstract 3215: BloodCCD is a novel biomarker to detect circadian rhythm disruption in cancer survivors with insomnia

Abstract Introduction: Insomnia is a significant co-morbidity for cancer survivors, and can independently reduce lifespan, but there is currently no objective biochemical measure of insomnia. Circadian rhythms are 24 hour cycles that control physiologic processes including sleep. Disrupted circadian rhythms have been proposed as a cause of insomnia. Here, we describe the use of a novel biomarker, BloodCCD, to assess circadian rhythms from RNA-sequencing of blood samples from two independent clinical trials and one observational study. BloodCCD was adapted from Clock Correlation Distance (CCD), which assesses normal progression of the molecular circadian clock from gene expression in tissue samples. We used BloodCCD to interrogate whether 1) cancer patients and survivors with insomnia have disrupted circadian rhythms compared to healthy good sleepers, and 2) whether the degree of circadian disruption correlates with severity of insomnia in survivors. Methods: For BloodCCD analysis, time-series RNA-sequencing of human blood from healthy subjects were used to construct a reference correlation matrix of 42 genes which oscillate with 24-hour rhythms. To assess the Aims, RNA-sequencing from patient and survivor blood samples were compared to this reference correlation matrix to generate a BloodCCD score. A higher score indicates a further distance from a healthy clock, and thus clock disruption. For the first Aim, blood RNA-sequencing from cancer patients undergoing active treatment and survivors at least 2-months post-treatment and with insomnia were compared to healthy good sleepers. For the second Aim, blood RNA-sequencing from cancer survivors with insomnia were assessed, stratified by Insomnia Severity Index (ISI) Score into mild (ISI 10-14), moderate (ISI 15-21), and severe (ISI 22-28) insomnia. Results: Patients (n=28, 100% prostate cancer) and cancer survivors (n=497, ~72% breast cancer) had higher BloodCCD scores, indicating disrupted circadian clock, compared to healthy good sleepers (n=14), with scores of 9.98, 7.99, and 4.13, respectively. When cancer survivors were stratified by insomnia severity, those with severe insomnia (ISI 22-28) had the highest BloodCCD, 9.00, while those with moderate insomnia (ISI 15-21) had a score of 8.24 and those with mild insomnia (ISI 10-14) had the lowest score of 7.93, indicating that survivors with severe insomnia had a more disrupted circadian clock. All BloodCCD values were p &amp;lt; 0.001 for each value compared to reference correlation. Conclusions: BloodCCD shows promise as a biomarker to biochemically detect disrupted circadian rhythms in cancer patients and survivors, and as a readout for insomnia severity. Future studies should investigate whether BloodCCD improves in cancer survivors receiving interventions for insomnia. Funding: UG1CA189961-07S1 (NCI BIQSFP Program), UG1CA189961 (URCC NCORP), T32CA102618 (URCC T32 program), K07CA221931 Citation Format: Brian J. Altman, Javier Bautista, Eva Culakova, Kristina M. Morris, Rachel E. DeRollo, Elliot Outland, Amber Kleckner, Ian R. Kleckner, Nikesha J. Gilmore, Benjamin T. Esparaz, Charles S. Kuzma, Amy C. Vander Woude, Po-Ju Lin, Jacob J. Hughey, Karen M. Mustian. BloodCCD is a novel biomarker to detect circadian rhythm disruption in cancer survivors with insomnia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3215.

The effect of wind turbine noise on polysomnographically measured and self-reported sleep latency in wind turbine noise naïve participants.

Wind turbine noise (WTN) exposure could potentially interfere with the initiation of sleep. However, effects on objectively assessed sleep latency are largely unknown. This study sought to assess the impact of WTN on polysomnographically measured and sleep diary-determined sleep latency compared to control background noise alone in healthy good sleepers without habitual prior WTN exposure. Twenty-three WTN naïve urban residents (mean ± SD age: 21.7 ± 2.1 years, range 18-29, 13 females) attended the sleep laboratory for two polysomnography studies, one week apart. Participants were blind to noise conditions and only informed that they may or may not hear noise during each night. During the sleep onset period, participants were exposed to counterbalanced nights of WTN at 33 dB(A), the upper end of expected indoor values; or background noise alone as the control condition (23 dB(A)). Linear mixed model analysis revealed no differences in log10 normalized objective or subjective sleep latency between the WTN versus control nights (median [interquartile range] objective 16.5 [11.0 to 18.5] vs. 16.5 [10.5 to 29.0] min, p = .401; subjective 20.0 [15.0 to 25.0] vs. 15.0 [10.0 to 30.0] min, p = .907). Although undetected small effects cannot be ruled out, these results do not support that WTN extends sleep latency in young urban-dwelling individuals without prior WTN exposure.

The impact of daily caffeine intake on nighttime sleep in young adult men

Acute caffeine intake can delay sleep initiation and reduce sleep intensity, particularly when consumed in the evening. However, it is not clear whether these sleep disturbances disappear when caffeine is continuously consumed during daytime, which is common for most coffee drinkers. To address this question, we investigated the sleep of twenty male young habitual caffeine consumers during a double-blind, randomized, crossover study including three 10-day conditions: caffeine (3 × 150 mg caffeine daily), withdrawal (3 × 150 mg caffeine for 8 days, then switch to placebo), and placebo (3 × placebo daily). After 9 days of continuous treatment, electroencephalographically (EEG)-derived sleep structure and intensity were recorded during a scheduled 8-h nighttime sleep episode starting 8 (caffeine condition) and 15 h (withdrawal condition) after the last caffeine intake. Upon scheduled wake-up time, subjective sleep quality and caffeine withdrawal symptoms were assessed. Unexpectedly, neither polysomnography-derived total sleep time, sleep latency, sleep architecture nor subjective sleep quality differed among placebo, caffeine, and withdrawal conditions. Nevertheless, EEG power density in the sigma frequencies (12–16 Hz) during non-rapid eye movement sleep was reduced in both caffeine and withdrawal conditions when compared to placebo. These results indicate that daily caffeine intake in the morning and afternoon hours does not strongly impair nighttime sleep structure nor subjective sleep quality in healthy good sleepers who regularly consume caffeine. The reduced EEG power density in the sigma range might represent early signs of overnight withdrawal from the continuous presence of the stimulant during the day.

Hyperarousal Is Associated with Socioemotional Processing in Individuals with Insomnia Symptoms and Good Sleepers.

Despite complaints of difficulties in waking socioemotional functioning by individuals with insomnia, only a few studies have investigated emotion processing performance in this group. Additionally, the role of sleep in socioemotional processing has not been investigated extensively nor using quantitative measures of sleep. Individuals with insomnia symptoms (n = 14) and healthy good sleepers (n = 15) completed two nights of at-home polysomnography, followed by an afternoon of in-lab performance testing on tasks measuring the processing of emotional facial expressions. The insomnia group self-reported less total sleep time, but no other group differences in sleep or task performance were observed. Greater beta EEG power throughout the night was associated with higher intensity ratings of happy, fearful and sad faces for individuals with insomnia, yet blunted sensitivity and lower accuracy for good sleepers. Thus, the presence of hyperarousal differentially impacted socioemotional processing of faces in individuals with insomnia symptoms and good sleepers.

Estimating sleep parameters using an accelerometer without sleep diary

Wrist worn raw-data accelerometers are used increasingly in large-scale population research. We examined whether sleep parameters can be estimated from these data in the absence of sleep diaries. Our heuristic algorithm uses the variance in estimated z-axis angle and makes basic assumptions about sleep interruptions. Detected sleep period time window (SPT-window) was compared against sleep diary in 3752 participants (range = 60–82 years) and polysomnography in sleep clinic patients (N = 28) and in healthy good sleepers (N = 22). The SPT-window derived from the algorithm was 10.9 and 2.9 minutes longer compared with sleep diary in men and women, respectively. Mean C-statistic to detect the SPT-window compared to polysomnography was 0.86 and 0.83 in clinic-based and healthy sleepers, respectively. We demonstrated the accuracy of our algorithm to detect the SPT-window. The value of this algorithm lies in studies such as UK Biobank where a sleep diary was not used.

Adverse impact of nocturnal transportation noise on glucose regulation in healthy young adults: Effect of different noise scenarios

BackgroundEpidemiological evidence indicates an association between transportation noise exposure and a higher risk of developing type 2 diabetes. Sleep disturbances are thought to be one of the mechanisms as it is well established that a few nights of short or poor sleep impair glucose tolerance and insulin sensitivity in healthy good sleepers. ObjectivesThe present study aimed to determine the extent to which exposure to nocturnal transportation noise affects glucose metabolism, and whether it is related to noise-induced sleep alterations. MethodsTwenty-one young healthy volunteers (nine women) participated in a six-day laboratory study starting with a noise-free baseline night, then four nights sleeping with randomly-presented transportation noise scenarios (three road and one railway noise scenario) with identical average sound level of 45dB but differing in eventfulness and ending with a noise-free recovery night. Sleep was measured by polysomnography. Glucose tolerance and insulin sensitivity were measured after the baseline, the last noise night and the recovery nights with an oral glucose tolerance test using Matsuda and Stumvoll insulin sensitivity indexes. Eleven participants were assigned a less eventful noise scenario during the last noise night (LE-group), while the other ten had a more eventful noise scenario (ME-group). Baseline metabolic and sleep variables between the two intervention groups were compared using a non-parametric Mann-Whitney U test while mixed models were used for repeated measure analysis. ResultsAll participants had increased glucoseAUC (mean±SE, 14±2%, p<0.0001) and insulinAUC (55±10%, p<0.0001) after the last noise night compared to the baseline night. 2h-glucose level tended to increase only in the ME-group between baseline (5.1±0.22mmol·L−1) and the last noise night (6.1±0.39mmol·L−1, condition: p=0.001, interaction: p=0.08). Insulin sensitivity assessed with Matsuda and Stumvoll indexes respectively decreased by 7±8% (p=0.001) and 9±2% (p<0.0001) after four nights with transportation noise. Only participants in the LE-group showed beneficial effects of the noise-free recovery night on glucose regulation (relative change to baseline: glucoseAUC: 1±2%, p=1.0 for LE-group and 18±4%, p<0.0001 for ME-group; Stumvoll index: 3.2±2.6%, p=1.0 for LE-group and 11±2.5%, p=0.002 for ME-group). Sleep was mildly impaired with increased sleep latency of 8±2min (<0.0001) and more cortical arousals per hour of sleep (1.8±0.6arousals/h, p=0.01) during the last noise night compared to baseline. No significant associations between sleep measures and glucose tolerance and insulin sensitivity were found. ConclusionIn line with epidemiological findings, sleeping four nights with transportation noise impaired glucose tolerance and insulin sensitivity. Based on the presented sound exposure, the eventfulness of the noise scenarios seems to play an important role for noise-induced alterations in glucose regulation. However, we could not confirm our hypothesis that transportation noise impairs glucose regulation via deterioration in sleep quality and quantity. Therefore, other factors, such as stress-related pathways, may need to be considered as potential triggers for noise-evoked glucose intolerance in future research.

Patients with chronic insomnia disorder have increased serum levels of neurofilaments, neuron-specific enolase and S100B: does organic brain damage exist?

ObjectivesThe aims of this study were to investigate whether serum levels of neurofilaments heavy chain (NfH) and light chain (NfL), neuron-specific enolase (NSE) and S100 calcium binding protein B (S100B): (1) change, (2) alleviate in post-therapy and (3) are associated with sleep quality and cognitive dysfunction, in patients with chronic insomnia disorder (CID). MethodsForty CID outpatients constituted free-therapy group (ft-CID), in which twenty-four patients completed follow-up after six-month treatment to form re-visiting group (rv-CID), and twenty healthy good sleepers constituted control group (HC). All subjects completed questionnaires, polysomnography, Chinese-Beijing Version of Montreal Cognitive Assessment (MoCA-C) and Nine Box Maze Test (NBMT) to assess sleep and neuropsychological function. The serum levels of NfH, NfL, NSE and S100B were detected using enzyme-linked immunosorbent assay. ResultsThe ft-CID had higher levels of NfH, NfL, NSE and S100B than the HC. Of note, the levels of NfH, NfL and NSE were significantly reduced in the rv-CID compared to the ft-CID, but not the level of S100B. Principal components analysis revealed that in these serum biomarkers, NfL and S100B had a substantial correlation with subjective and objective sleep parameters. ConclusionsThe CID patients had elevated serum levels of NfH, NfL, NSE and S100B, indicating existence of damaged brain microstructure, including neurons, astrocytes and neuronal terminals, which were associated with the insomniac severity or/and cognitive dysfunction and could significantly reduce after effective therapy apart from the S100B.

Rest but busy: Aberrant resting-state functional connectivity of triple network model in insomnia.

IntroductionOne classical hypothesis among many models to explain the etiology and maintenance of insomnia disorder (ID) is hyperarousal. Aberrant functional connectivity among resting‐state large‐scale brain networks may be the underlying neurological mechanisms of this hypothesis. The aim of current study was to investigate the functional network connectivity (FNC) among large‐scale brain networks in patients with insomnia disorder (ID) during resting state.MethodsIn the present study, the resting‐state fMRI was used to evaluate whether patients with ID showed aberrant FNC among dorsal attention network (DAN), frontoparietal control network (FPC), anterior default mode network (aDMN), and posterior default mode network (pDMN) compared with healthy good sleepers (HGSs). The Pearson's correlation analysis was employed to explore whether the abnormal FNC observed in patients with ID was associated with sleep parameters, cognitive and emotional scores, and behavioral performance assessed by questionnaires and tasks.ResultsPatients with ID had worse subjective thought control ability measured by Thought Control Ability Questionnaire (TCAQ) and more negative affect than HGSs. Intriguingly, relative to HGSs, patients with ID showed a significant increase in FNC between DAN and FPC, but a significant decrease in FNC between aDMN and pDMN. Exploratory analysis in patients with ID revealed a significantly positive correlation between the DAN‐FPC FNC and reaction time (RT) of psychomotor vigilance task (PVT).ConclusionThe current study demonstrated that even during the resting state, the task‐activated and task‐deactivated large‐scale brain networks in insomniacs may still maintain a hyperarousal state, looking quite similar to the pattern in a task condition with external stimuli. Those results support the hyperarousal model of insomnia.

Limited Efficacy of Caffeine and Recovery Costs During and Following 5 Days of Chronic Sleep Restriction.

To investigate the effects of caffeine on psychomotor vigilance and sleepiness during sleep restriction and following subsequent recovery sleep. Participants were N = 48 healthy good sleepers. All participants underwent five nights of sleep satiation (time-in-bed [TIB]: 10 hours), followed by five nights of sleep restriction (TIB: 5 hours), and three nights of recovery sleep (TIB: 8 hours) in a sleep laboratory. Caffeine (200 mg) or placebo was administered in the form of chewing gum at 08:00 am and 12:00 pm each day during the sleep restriction phase. Participants completed hourly 10-minute psychomotor vigilance tests and a modified Maintenance of Wakefulness Test approximately every 4 hours during the sleep restriction and recovery phases. Caffeine maintained objective alertness compared to placebo across the first 3 days of sleep restriction, but this effect was no longer evident by the fourth day. A similar pattern of results was found for Maintenance of Wakefulness Test sleep latencies, such that those in the caffeine group (compared to placebo) did not show maintenance of wakefulness relative to baseline after the second night of restriction. Compared to placebo, participants in the caffeine condition displayed slower return to baseline in alertness and wakefulness across the recovery sleep period. Finally, the caffeine group showed greater N3 sleep duration during recovery. Caffeine appears to have limited efficacy for maintaining alertness and wakefulness across 5 days of sleep restriction. Perhaps more importantly, there may be recovery costs associated with caffeine use following conditions of prolonged sleep loss.

매트리스의 종류가 건강한 성인의 주관적, 객관적 수면의 질에 미치는 영향에 대한 탐색적 연구

목 적 : 일반스프링 매트리스에 비교하여 지지력 등을 향상시킨 컨투어 코일 매트리스가 주관적 및 객관적인 수면의 질을 향상시킬 수 있는지 알아보고자 하였다. 방 법 : 건강하게 수면하는 일반인 대상자 15명을 모집하였다. 연구대상자들은 두 종류의 매트리스에서 잠을 자면서 야간수면다원검사를 시행하였고 검사 전, 후 주관적인 수면의 질에 대한 자가설문지를 작성하게 하였다. 한 연구대상자가 각각 다른 매트리스에서 2일에 걸쳐 야간수면다원검사를 시행하여 얻어진 객관적인 수면변인들과 주관적인 자가 설문지 변수들로 교차설계분석을 시행하였다. 결 과 : 야간수면다원검사에서 측정된 수면잠복기가 컨투어 코일 매트리스에서 잠을 잔 경우 일반스프링 매트리스에서 잠을 잔 경우보다 평균 1.9분 감소하였다. 이외에도 주관적으로 느낀 수면 중 각성횟수, 깊게 잠든 느낌 그리고 잠자리의 편안함이 컨투어 코일 매트리스가 유의하게 더 나은 결과를 보였다. 결 론 : 매트리스가 종류에 따라서 주관적인 수면의 질뿐만 아니라 객관적인 수면의 질에도 영향을 미친다고 할 수 있다. Objectives: We aimed to evaluate the effects of mattress type on both objective and subjective sleep quality in healthy good sleepers. Methods: Fifteen healthy good sleepers with a mean age of 30.8 years participated in this study. A randomized crossover trial was carried out using two different mattress types: a standard mattress and a contour coil mattress. After a night of adaptation, all participants were randomized to either a standard mattress or a contour coil mattress. Then, nocturnal polysomnography was conducted for two consecutive nights. Subjective evaluations were obtained using a self-report questionnaire before and after the polysomnographic recording sessions. Results: The polysomnographic showed no differences in total sleep time, sleep stage, or wake time after sleep onset between the two mattress conditions. Of the polysomnographic variables, only sleep onset latency was significantly reduced for the contour coil mattress. Additionally, participants reported better subjective sleep quality when sleeping on the contour coil mattress, according to the questionnaires. Conclusion: The type of mattress might affect not only subjective, but also objective sleep quality, including sleep onset latency.

Magnetic Resonance Spectroscopy in Patients with Insomnia: A Repeated Measurement Study.

Chronic insomnia is one of the most prevalent central nervous system disorders. It is characterized by increased arousal levels, however, the neurobiological causes and correlates of hyperarousal in insomnia remain to be further determined. In the current study, magnetic resonance spectroscopy was used in the morning and evening in a well-characterized sample of 20 primary insomnia patients (12 females; 8 males; 42.7 ± 13.4 years) and 20 healthy good sleepers (12 females; 8 males; 44.1 ± 10.6 years). The most important inhibitory and excitatory neurotransmitters of the central nervous system, γ-aminobutyric acid (GABA) and glutamate/glutamine (Glx), were assessed in the anterior cingulate cortex (ACC) and dorsolateral prefrontal cortex (DLPFC). The primary hypothesis, a diurnal effect on GABA levels in patients with insomnia, could not be confirmed. Moreover, the current results did not support previous findings of altered GABA levels in individuals with insomnia. Exploratory analyses, however, suggested that GABA levels in the ACC may be positively associated with habitual sleep duration, and, thus, reduced GABA levels may be a trait marker of objective sleep disturbances. Moreover, there was a significant GROUP x MEASUREMENT TIME interaction effect on Glx in the DLPFC with increasing Glx levels across the day in the patients but not in the control group. Therefore, Glx levels may reflect hyperarousal at bedtime in those with insomnia. Future confirmatory studies should include larger sample sizes to investigate brain metabolites in different subgroups of insomnia.

(190) Effects of sleep continuity disruption on cold pain tolerance and accompanying pain catastrophizing in healthy, good sleepers

Chronic sleep problems, such as those associated with insomnia, have been shown to increase vulnerability for chronic pain at the population level. However, there is limited understanding of the mechanisms linking sleep and pain. Cold pain tolerance (CPT) is a predictor of clinical pain severity in chronic pain patients. Pain catastrophizing, a maladaptive cognitive coping strategy, is associated with lower pain tolerance and higher clinical pain. In the present study, we investigated the effects of sleep continuity disruption -- an experimental model of sleep deprivation with ecological validity for comorbid chronic pain and insomnia -- on CPT and accompanying catastrophizing cognitions. Healthy good sleepers underwent one night of uninterrupted sleep (US) and one night of forced awakenings (FA) in a randomized, within-person, counter-balanced design. On the day following each sleep condition, participants placed their dominant hand palm-down in a 4°C circulating water bath for a maximum of 300 seconds and were instructed to remove their hand when the pain became intolerable. CPT was measured as the time to withdrawal. Participants completed a self-report pain catastrophizing scale immediately following CPT. A total of 33 subjects provided usable data on these measures. Results indicated that CPT was significantly lower following FA compared to US (p<0.05). Pain catastrophizing was not significantly different between sleep conditions. Together these findings indicate that a single night of sleep continuity disruption is associated with a reduction in CPT that does not appear to be driven by catastrophizing. The present data suggest that the association of sleep continuity disruption and pain tolerance may be one avenue through which chronic sleep disorders, such as insomnia, increase vulnerability to chronic pain.

Successful physical exercise-induced weight loss is modulated by habitual sleep duration in the elderly: results of a pilot study.

Although it is widely accepted that physical exercise promotes weight loss, physical exercise alone had been found to result in only marginal weight loss compared to no treatment. Interestingly, both subjective and objective sleep duration have been shown to be negatively correlated to the body mass index (BMI). Despite this growing evidence of a relation between sleep duration and body weight, the role of habitual sleep duration in physical exercise-induced weight loss has not been studied so far. Twenty-two healthy elderly good sleepers aged 61-76years (mean 68.36years, 55% female, BMI mean 25.15kg/m2) either took part in a 12-week aerobic endurance training (3×30min/week) or in a relaxation control (2×45min/week). The BMI was assessed prior to and after intervention. Subjects maintained sleep logs every morning/evening during the training period, allowing for calculation of habitual sleep duration. Besides a significant main effect of the type of training, a significant interaction of type of training and habitual sleep duration was observed: while after treadmill training subjects who slept less than 7.5h/night during intervention reduced their BMI by nearly 4%, a comparable decrease in the BMI was found neither in subjects who slept more than 7.5h nor after relaxation training independent of sleep duration. Sleep duration itself did not change in any group. Although results should be interpreted with caution due to the small sample size, this is the first study to indicate that physical exercise might compensate for disturbed body weight regulation associated with short sleep duration.

Analysis of A-phase transitions during the cyclic alternating pattern under normal sleep.

An analysis of the EEG signal during the B-phase and A-phases transitions of the cyclic alternating pattern (CAP) during sleep is presented. CAP is a sleep phenomenon composed by consecutive sequences of A-phases (each A-phase could belong to a possible group A1, A2 or A3) observed during the non-REM sleep. Each A-phase is separated by a B-phase which has the basal frequency of the EEG during a specific sleep stage. The patterns formed by these sequences reflect the sleep instability and consequently help to understand the sleep process. Ten recordings from healthy good sleepers were included in this study. The current study investigates complexity, statistical and frequency signal properties of electroencephalography (EEG) recordings at the transitions: B-phase--A-phase. In addition, classification between the onset-offset of the A-phases and B-phase was carried out with a kNN classifier. The results showed that EEG signal presents significant differences (p < 0.05) between A-phases and B-phase for the standard deviation, energy, sample entropy, Tsallis entropy and frequency band indices. The A-phase onset showed values of energy three times higher than B-phase at all the sleep stages. The statistical analysis of variance shows that more than 80% of the A-phase onset and offset is significantly different from the B-phase. The classification performance between onset or offset of A-phases and background showed classification values over 80% for specificity and accuracy and 70% for sensitivity. Only during the A3-phase, the classification was lower. The results suggest that neural assembles that generate the basal EEG oscillations during sleep present an over-imposed coordination for a few seconds due to the A-phases. The main characteristics for automatic separation between the onset-offset A-phase and the B-phase are the energy at the different frequency bands.

Correction: The Relationship between Brain Morphology and Polysomnography in Healthy Good Sleepers

Correction: The Relationship between Brain Morphology and Polysomnography in Healthy Good Sleepers

Insomnia disorder is associated with increased amygdala reactivity to insomnia-related stimuli.

Alterations in emotional reactivity may play a key role in the pathophysiology of insomnia disorder (ID). However, only few supporting experimental data are currently available. We evaluated in a hypothesis-driven design whether patients with ID present altered amygdale responses to emotional stimuli related and unrelated to the experience of insomnia and, because of chronic hyperarousal, less habituation of amygdala responses. Case-control study. Departments of Psychiatry and Psychotherapy and of Radiology of the University of Freiburg Medical Center. There were 22 patients with ID (15 females; 7 males; age 40.7 ± 12.6 y) and 38 healthy good sleepers (HGS, 21 females; 17 males; age 39.6 ± 8.9 y). N/A. In a functional magnetic resonance imaging session, five different blocks of pictures with varying emotional arousal, valence, and content (insomnia-relatedness) were presented. Pictures were presented twice to test for habituation processes. Results showed that patients with ID, compared to HGS, presented heightened amygdala responses to insomnia-related stimuli. Moreover, habituation of amygdale responses was observed only in HGS, but not in patients with ID who showed a mixed pattern of amygdala responses to the second presentation of the stimuli. The results provide evidence for an insomnia-related emotional bias in patients with ID. Cognitive behavior treatment for ID could benefit from strategies dealing with the emotional charge associated with the disorder. Further studies should clarify the role of ID with respect to habituation of amygdala responses.

The relationship between brain morphology and polysomnography in healthy good sleepers.

BackgroundNormal sleep continuity and architecture show remarkable inter-individual variability. Previous studies suggest that brain morphology may explain inter-individual differences in sleep variables.MethodThirty-eight healthy subjects spent two consecutive nights at the sleep laboratory with polysomnographic monitoring. Furthermore, high-resolution T1-weighted MRI datasets were acquired in all participants. EEG sleep recordings were analyzed using standard sleep staging criteria and power spectral analysis. Using the FreeSurfer software for automated segmentation, 174 variables were determined representing the volume and thickness of cortical segments and the volume of subcortical brain areas. Regression analyses were performed to examine the relationship with polysomnographic and spectral EEG power variables.ResultsThe analysis did not provide any support for the a-priori formulated hypotheses of an association between brain morphology and polysomnographic variables. Exploratory analyses revealed that the thickness of the left caudal anterior cingulate cortex was positively associated with EEG beta2 power (24–32 Hz) during REM sleep. The volume of the left postcentral gyrus was positively associated with periodic leg movements during sleep (PLMS).ConclusionsThe function of the anterior cingulate cortex as well as EEG beta power during REM sleep have been related to dreaming and sleep-related memory consolidation, which may explain the observed correlation. Increased volumes of the postcentral gyrus may be the result of increased sensory input associated with PLMS. However, due to the exploratory nature of the corresponding analyses, these results have to be replicated before drawing firm conclusions.