Insomnia and sleep misperception

A continuous approach to explain insomnia and subjective-objective sleep discrepancy

Understanding insomnia is crucial for improving its diagnosis and treatment. However, many subjective complaints about insomnia do not align with objective measures of sleep quality, as is the case in subjective-objective sleep discrepancy (SOSD). We address this discrepancy by measuring sleep intrusions and instability in polysomnographic recordings from a large clinical database. Using machine learning, we develop personalized models to infer hypnodensities-a continuous and probabilistic measure of sleep dynamics-, and analyze them via information theory to measure intrusions and instability in a principled way. We find that insomnia with SOSD involves sleep intrusions during intra-sleep wakefulness, while insomnia without SOSD shows wake intrusions during sleep, indicating distinct etiologies. By mapping these metrics to standard sleep features, we provide a continuous and interpretable framework for measuring sleep quality. This approach integrates and values subjective insomnia complaints with physiological data for a more accurate view of sleep quality and its disorders.

Harnessing technology to improve sleep in frontline healthcare workers: A pilot study of electronic noise-masking earbuds on subjective and objective sleep measures

Objective: This pilot study assessed the effects of electronic noise-masking earbuds on subjective sleep perception and objective sleep parameters among healthcare workers (HCWs) reporting sleep difficulties during the COVID-19 pandemic. Methods: Using a pre-post design, 77 HCWs underwent 3 nights of baseline assessment followed by a 7-night intervention period. Participants wore an at-home sleep monitoring headband to assess objective sleep measures and completed subjective self-report assessments. The difference in mean sleep measures from baseline to intervention was estimated in linear mixed models. Results: Compared to baseline assessments, HCWs reported significant improvements in sleep quality as measured by the Insomnia Severity Index (ISI) (Cohen's d = 1.74, p < 0.001) and a significant reduction in perceived sleep onset latency (SOL) during the intervention (M = 17.2 minutes, SD = 7.7) compared to baseline (M = 24.7 minutes, SD = 16.1), (Cohen's d = -0.42, p = 0.001). There were no significant changes in objective SOL (p = 0.703). However, there was a significant interaction between baseline objective SOL (<20 minutes vs >20 minutes) and condition (baseline vs intervention) (p = 0.002), such that individuals with objective SOL >20 minutes experienced a significant decrease in objective SOL during the intervention period compared to baseline (p = 0.015). Conclusions: HCWs experienced a significant improvement in perceived SOL and ISI scores after using the electronic noise-masking earbuds. Our data provide preliminary evidence for a nonpharmacological intervention to improve the sleep quality of HCWs which should be confirmed by future controlled studies.

Measuring Objective and Subjective Sleep during Lisdexamfetamine Treatment of Acute Methamphetamine Withdrawal: A Feasibility Study

INTRODUCTION

Sleep disturbance is common during methamphetamine (MA) use and withdrawal; however, the feasibility of combined subjective-objective measurement of sleep-wake has not been shown in this population. Actigraphy is a well-established, non-invasive measure of sleep-wake cycles with good concordance with polysomnography. This study aimed to investigate the feasibility and utility of using actigraphy and sleep diaries to investigate sleep during MA withdrawal.

METHODS

We conducted a feasibility and utility study of actigraphy and sleep diaries during a clinical trial of lisdexamfetamine for MA withdrawal. Participants were inpatients for 7 days, wore an actigraph (Philips Actiwatch 2) and completed a modified Consensus Sleep Diary each morning. Participants were interviewed between days 3-5.

RESULTS

Ten participants (mean age 37 years, 90% male) were enrolled. No participant removed the device prematurely. Participants interviewed (n = 8) reported that the actigraph was not difficult or distracting to wear or completion of daily sleep diary onerous. Actigraphic average daily sleep duration over 7 days was 568 min, sleep onset latency 22.4 min, wake after sleep onset (WASO) 75.2 min, and sleep efficiency 83.6%. Sleep diaries underreported daily sleep compared with actigraphy (sleep duration was 56 min (p = 0.008) and WASO 47 min (p < 0.001) less). Overall sleep quality was 4.4 on a nine-point Likert scale within the diary.

CONCLUSIONS

Continuous actigraphy is feasible to measure sleep-wake in people withdrawing from MA, with low participant burden. We found important differences in self-reported and actigraphic sleep, which need to be explored in more detail.

Methodological approach to sleep state misperception in insomnia disorder: Comparison between multiple nights of actigraphy recordings and a single night of polysomnography recording

STUDY OBJECTIVE

To provide a comprehensive assessment of sleep state misperception in insomnia disorder (INS) and good sleepers (GS) by comparing recordings performed for one night in-lab (PSG and night review) and during several nights at-home (actigraphy and sleep diaries).

METHODS

Fifty-seven INS and 29 GS wore an actigraphy device and filled a sleep diary for two weeks at-home. They subsequently completed a PSG recording and filled a night review in-lab. Sleep perception index (subjective/objective × 100) of sleep onset latency (SOL), sleep duration (TST) and wake duration (TST) were computed and compared between methods and groups.

RESULTS

GS displayed a tendency to overestimate TST and WASO but correctly perceived SOL. The degree of misperception was similar across methods within the GS group. In contrast, INS underestimated their TST and overestimated their SOL both in-lab and at-home, yet the severity of misperception of SOL was larger at-home than in-lab. Finally, INS overestimated WASO only in-lab while correctly perceiving it at-home. While only the degree of TST misperception was stable across methods in INS, misperception of SOL and WASO were dependent on the method used.

CONCLUSIONS

We found that GS and INS exhibit opposite patterns and severity of sleep misperception. While the degree of misperception in GS was similar across methods, only sleep duration misperception was reliably detected by both in-lab and at-home methods in INS. Our results highlight that, when assessing sleep misperception in insomnia disorder, the environment and method of data collection should be carefully considered.

Neurophysiological Parameters Influencing Sleep-Wake Discrepancy in Insomnia Disorder: A Preliminary Analysis on Alpha Rhythm during Sleep Onset

Sleep state misperception (SSM) is a common issue in insomnia disorder (ID), causing a discrepancy between objective and subjective sleep/wake time estimation and increased daytime impairments. In this context, the hyperarousal theory assumes that sustained central nervous system activation contributes to the SSM. This study investigates factors influencing SSM during sleep latency (SL) and total sleep time (TST). Objective polysomnographic sleep variables (the alpha density index, latency-to-sleep stages and the first K-complex, and Rapid Eye Movement (REM) arousal density) and subjective sleep indices, taken from sleep diaries, were analyzed in 16 ID patients. Correlation analyses revealed a positive association between the degree of SL misperception (SLm) and the percentage of epochs that contained a visually scored stereotyped alpha rhythm during objective SL. A regression analysis showed that the REM arousal density and alpha density index significantly predicted TST misperception (TSTm). Furthermore, the degree of SLm was associated with an increased probability of transitioning from stage 1 of non-REM sleep to wakefulness during subjective SL. These findings support the role of hyperarousal in SSM and highlight the importance of alpha activity in unravelling the heterogeneous underpinnings of SSM.

Quantile regression to explore association of sleep duration with depression among adults in NHANES and KNHANES

BACKGROUND

Sleep duration has been associated with depression. However, mean regression, such as linear regression or logistic regression, may not capture relationships that occur mainly in the tails of outcome distribution. This study aimed to evaluate the associations between sleep duration and depression along the entire distribution of depression using quantile regression approach.

METHODS

This study included 55,954 adults aged 18 to 80 years from the National Health and Nutrition Examination Survey (N = 34,156) and the Korea National Health and Nutrition Examination Survey (N = 21,798). The coefficients corresponding to cross-group differences in PHQ-9 scores were estimated when comparing short or long sleep duration with normal sleep duration on deciles of PHQ-9 score distribution.

RESULTS

At lower quantiles, either short or long sleep duration was not associated with depression. At higher quantiles, the association of both short and long sleep duration with depression became much more pronounced. Compared with normal sleep duration, short and long sleep duration were associated with increases of 1.34 (95 % CI: 1.16, 1.51) and 0.28 (95 % CI: 0.04, 0.52) in PHQ-9 scores at the 50th quantile, while the corresponding increases were 3.27 (95 % CI: 2.83, 3.72) and 1.65 (95 % CI: 0.86, 2.45) at the 90th quantile, respectively. We also found that the magnitude of association between short sleep duration and depression was stronger among females and individuals with chronic diseases.

CONCLUSIONS

The beneficial effect of sufficient sleep in decreasing depression severity may be more evident among individuals with severe depression. Further studies could explore whether these heterogeneous associations can be generalized to populations with different characteristics.

Sleep-wake state discrepancy among cancer survivors with insomnia symptoms

PURPOSE

To evaluate the discrepancy and correlation between sleep-wake measures (i.e., time in bed (TIB), total sleep time (TST), sleep onset latency (SOL), wake after sleep onset (WASO), and sleep efficiency (SE%)) reported on sleep diary and measured by actigraphy among cancer survivors with insomnia symptoms; and examine the influences of sociodemographic and clinical variables on these measurement differences.

METHODS

A heterogenous sample of cancer survivors with insomnia symptoms (n = 120; M age = 63.7 ± 10.1; female = 58.3%) was included. Seven consecutive days of sleep diary and actigraphic data were obtained along with information on demographic, sleep, and mental health symptoms. Bland-Altman plot, Pearson correlation coefficient, concordance correlation coefficient, and mixed linear model approach were used to conduct the analysis.

RESULTS

Self-reported TIB, SOL, and WASO were longer than measured by actigraphy (TIB: 8.6 min. (95% CI, 3.7, 13.5; p < .001); SOL: 14.8 min. (95% CI, 9.4, 20.2; p < .0001); and WASO: 20.7 min. (95% CI, 9.4, 20.2; p < .0001), respectively); and self-reported TST and SE% were shorter than measured by actigraphy (TST: 6.8 min. (95% CI, -18.7, 5.13); and SE%: 0.7% (95%CI, -3.0, 2.0), respectively), but were not statistically significant. Sex, higher insomnia severity, and poor sleep quality were associated with discrepancy between several sleep-wake measures.

CONCLUSION

Subjective and objective sleep-wake measures may present discrepant finding among cancer survivors with symptoms of insomnia. Future research is needed to validate appropriate sleep-wake assessment, and better understand factors that influence the discrepancy that exists between measures among this population.

CLINICAL TRIAL REGISTRATION

Clinical trials identifier: NCT03810365. Date of registration: January 14, 2019.

Effects of red light on sleep and mood in healthy subjects and individuals with insomnia disorder

Introduction

This study aimed to determine the influence of red light on objective sleep and the relationship between mood and sleep among individuals with insomnia disorder (ID).

Method

57 individuals with insomnia symptoms and 57 healthy participants were randomly divided into three groups (red- and white-light groups, and the black control group), which received different light treatments for 1 h before bedtime. The emotions and subjective alertness of participants were evaluated using Positive and Negative Affect Schedule scales (PANAS) and Karolinska Sleepiness Scale (KSS), their sleeping data were recorded using polysomnography (PSG).

Result

The negative emotion scores were higher in the healthy subject-red light (HS-RL) group than in the HS-white light (WL) and HS-black control (BC) groups (p < 0.001). The anxiety and negative emotion scores were higher in the ID-RL group than in the ID-WL and ID-BC groups (p = 0.007 and p < 0.001, respectively). The KSS scores were lower in the RL group than in the WL and BC groups for both HS and ID group (both p < 0.001). The SOL was shorter in the HS-RL group than in HS-WL group (p = 0.019). Compared with the HS-BC group, the HS-RL group had an increase in microarousal index (MAI) and N1% (p = 0.034 and p = 0.021, respectively), while the total sleep time (TST) and sleep efficiency (SE) decreased (p = 0.001 and p < 0.001, respectively). Compared with the ID-WL group, the SOL was shorter in the ID-RL group (p = 0.043), while TST, SE, number of microarousals (NMA), and numbers of cycles of REM period were increased (p = 0.016, p = 0.046, p = 0.001, and p = 0.041, respectively). Compared with the ID-BC group, the ID-RL group had increases in the SOL, WASO, and the numbers of cycles and NMA in REM period (p = 0.038, p = 0.005, p = 0.045, and p = 0.033, respectively), and a decrease in SE (p = 0.014). The effects of ID-WL (vs. ID-RL group) and ID-BC (vs. ID-RL group) on SOL were mediated by negative emotions (mediating effects were - 37.626 and - 33.768, respectively).

Conclusion

Red light can increase subjective alertness, anxiety, and negative emotions in both healthy subjects and people with ID, which can affect sleep directly or indirectly via the mediating effect of negative emotions.

No alterations in potential indirect markers of locus coeruleus-norepinephrine function in insomnia disorder

The norepinephrine locus coeruleus system (LC NE) represents a promising treatment target in patients with insomnia disorder (ID) due to its well understood links to arousal and sleep regulation. However, consistent markers of LC NE activity are lacking. This study measured three potential indirect markers of LC NE activity - REM sleep, P3 amplitude during an auditory oddball paradigm (as a marker of phasic LC activation), and baseline pupil diameter (as a marker of tonic LC activation). The parameters were then combined in a statistical model and tested to compare LC NE activity between 20 subjects with insomnia disorder (13 female; age 44.2 ± 15.1 year) and 20 healthy, good sleeping controls (GSC; 11 female; age 45.4 ± 11.6 year). No group differences regarding the primary outcome parameters were detected. Specifically, insomnia disorder did not display the hypothesised changes in markers of LC NE function. While increased LC NE function remains an interesting speculative pathway for hyperarousal in insomnia disorder, the investigated markers do not appear closely related to each other and fail to discriminate between insomnia disorder and good sleeping controls in these samples.

Bidirectional Daily Associations Between Accelerometer-Measured Sleep and Physical Activity in Brazilian High School Students

PURPOSE

This study analyzed day-to-day estimates of bidirectional associations between sleep parameters and intensity-specific physical activity and assessed whether the timing of physical activity influences these relationships.

METHODS

The sample was comprised of 651 high school students (51.2% female, 16.33 [1.0] y old) from southern Brazil. Physical activity and sleep were measured using accelerometers. Multilevel models were applied to test associations of nocturnal total sleep time, onset, and efficiency with moderate to vigorous and light (LPA) physical activity.

RESULTS

Higher engagement in moderate to vigorous physical activity and LPA was associated with increased total sleep time, and this effect was greater when physical activity was performed in the morning. Morning and evening LPA were associated with increased sleep efficiency and reduced total sleep time, respectively. Practice of LPA in the morning leads to early sleep onset, whereas evening LPA was associated with later onset. Higher total sleep time and later sleep onset were associated with lower moderate to vigorous physical activity and LPA on the following day. However, higher sleep efficiency was associated with increased LPA.

CONCLUSION

The relationship between sleep parameters and physical activity is bidirectional and dependent on physical activity intensity and timing.

Sleep Continuity, Stability and Cyclic Organization Are Impaired in Insomniacs: A Case-Control Study

The possibility of distinguishing insomniacs from good sleepers based on polysomnography (PSG) remains an open question. While these groups show modest differences in traditional PSG parameters, some studies suggest that finer measures may be more useful. Here we assess differences between good sleepers (GS), poor sleepers (PS) and insomniacs (IN) in classical PSG measures as well as in sleep continuity, stability and cyclic organization. PSG-monitored sleep (two nights) of 17 IN (diagnosed through a standard clinical interview; Pittsburgh Sleep Quality Index (PSQI) ≥ 5, Insomnia Severity Index (ISI) > 14) was compared to that of 33 GS (PSQI < 5) and 20 PS (PSQI ≥ 5, ISI ≤ 14). Compared to GS, IN were impaired in sleep macrostructure (sleep latency, sleep efficiency, WASO%) and in continuity, stability and organization, whereas PS only showed disrupted continuity and stability. Spindle parameters were comparable between IN and GS, but the former displayed enhanced power in fast frequency bands. Our findings support the hypothesis of a continuum between individuals with self-reported poor sleep and insomniacs. Further, they add to extant data on impaired sleep continuity, stability and organization in poor sleepers and elderly individuals, underlining the utility of including these measures in standard sleep assessments.

Emerging applications of objective sleep assessments towards the improved management of insomnia

Self-reported sleep difficulties are the primary concern associated with diagnosis and treatment of chronic insomnia. This said, in-home sleep monitoring technology in combination with self-reported sleep outcomes may usefully assist with the management of insomnia. The rapid acceleration in consumer sleep technology capabilities together with their growing use by consumers means that the implementation of clinically useful techniques to more precisely diagnose and better treat insomnia are now possible. This review describes emerging techniques which may facilitate better identification and management of insomnia through objective sleep monitoring. Diagnostic techniques covered include insomnia phenotyping, better detection of comorbid sleep disorders, and identification of patients potentially at greatest risk of adverse outcomes. Treatment techniques reviewed include the administration of therapies (e.g., Intensive Sleep Retraining, digital treatment programs), methods to assess and improve treatment adherence, and sleep feedback to address concerns about sleep and sleep loss. Gaps in sleep device capabilities are also discussed, such as the practical assessment of circadian rhythms. Proof-of-concept studies remain needed to test these sleep monitoring-supported techniques in insomnia patient populations, with the goal to progress towards more precise diagnoses and efficacious treatments for individuals with insomnia.

Hypnotizability May Relate to Interoceptive Ability to Accurately Perceive Sleep Depth: An Exploratory Study

When individuals score high on hypnotizability, they usually report experiencing an altered state of consciousness, physiological changes, and attentional shifts during hypnotic induction procedures as well. We hypothesize that a better interoception of such internal changes is also relevant for accurate sleep perception. We compared subjects scoring high versus low on hypnotizability to the accuracy of their estimations of Sleep Onset Latency (SOL) time awake, and sleep depth and explored their objective sleep. We sampled seven studies performed in our sleep labs across a midday nap or a night resulting in n = 231 subjects (aged 30.11 (SD = 17.02) years, range 18-82 with 15.2% males). Hypnotizability did not influence the accuracy of the perception of time needed to fall asleep or time spent awake. However, the reported sleep depth correlated significantly with the measured amount of slow-wave sleep in high hypnotizables. This pattern appeared across a nap as well as a whole night's sleep studies. We did not find any significant differences in objective sleep patterns depending on hypnotizability. Probably, high hypnotizables benefit from a better interoceptive ability for their perception of their sleep depth.

The underestimation of sleep duration phenotype is associated with better treatment response to cognitive behavior therapy for insomnia in patients with chronic insomnia: a preliminary study

STUDY OBJECTIVES

To examine treatment response to cognitive behavior therapy for insomnia (CBT-I) in patients with chronic insomnia with and without underestimation of sleep duration.

METHODS

We studied 41 patients with chronic insomnia who had received 5-week CBT-I. Self-reported and objective sleep were assessed with sleep diary and actigraphy, respectively. Sleep perception was calculated as self-reported total sleep time/objective total sleep time. The underestimation of sleep duration group was defined based on sleep perception less than the median of the overall sample (85%). Insomnia Severity Index was used to assess the severity of insomnia.

RESULTS

The total scores of Insomnia Severity Index decreased significantly after CBT-I in both groups with and without underestimation of sleep duration. Compared to pretreatment, self-reported sleep efficiency increased and total wake time decreased after CBT-I, while the magnitude of changes in sleep efficiency (d = 1.40 vs d=0.81, interaction P = .016) and total wake time (d = -1.82 vs d = -0.85, interaction P < .001) were larger in the underestimation of sleep duration group . Furthermore, self-reported sleep onset latency (interaction P = .520) and wake after sleep onset (interaction P = .052) decreased in the underestimation of sleep duration group (all P < .05), but not in patients without underestimation of sleep duration. Linear regressions showed that lower sleep perception at baseline predicted greater increase in self-reported sleep efficiency (β = -0.99, P < .001) and total sleep time (β = -0.51, P = .006) and greater decrease in self-reported total wake time (β=1.22, P = .023) after CBT-I after adjusting for confounders.

CONCLUSIONS

The current preliminary study suggests that sleep perception moderates the self-reported CBT-I effects on chronic insomnia: the phenotype of underestimation of sleep duration is associated with a better response to CBT-I, especially in self-reported sleep parameters.

CITATION

Sun Q, Dai Y, Chen B, et al. The underestimation of sleep duration phenotype is associated with better treatment response to cognitive behavior therapy for insomnia in patients with chronic insomnia: a preliminary study. J Clin Sleep Med. 2022;18(10):2443-2450.

Association Between Subjective-Objective Discrepancy of Sleeping Time and Health-Related Quality of Life: A Community-Based Polysomnographic Study

OBJECTIVE

This study aimed to investigate the existence of a difference in quality of life (QOL) between individuals with and without significant subjective-objective discrepancy (SOD) in total sleep time (TST).

METHODS

From the Sleep Heart Health Study 2, 2540 individuals who had completed polysomnography, a morning sleep survey, and the 36-item Short-Form Health Survey (SF-36) were included in the analyses. The participants were classified as normoestimators (estimation of TST <±60 minutes), underestimators (underestimation of TST ≥60 minutes), or overestimators (overestimation of TST ≥60 minutes). The standardized SF-36 QOL scores were compared among the three groups. An adjusted partial correlation analysis was conducted between SOD and QOL.

RESULTS

Of the 2540 participants, 1617 (63.7%), 433 (17.0%), and 490 (19.3%) were assigned to the normoestimator, underestimator, and overestimator groups, respectively. The bodily pain and social functioning components of the SF-36 score were significantly lower in the underestimators than in the normoestimators, whereas the physical functioning component was significantly lower in the overestimators than in the normoestimators. The absolute value of SOD in the TST showed a significant negative correlation with the physical and mental components of the SF-36.

CONCLUSIONS

QOL was significantly better in the normoestimator than in the other groups and linearly correlated with the absolute value of SOD. This study suggests that a high prevalence of positive and negative sleep misperception in a community population can be a potential factor associated with poor QOL and potential comorbidities.

Sleep Misperception and Associated Factors in Patients With Anxiety-Related Disorders and Complaint of Insomnia: A Retrospective Study

Purpose

Data on sleep parameters by polysomnography (PSG) in patients with anxiety-related disorders are limited. Although the disturbance and risk factors of sleep misperception have been implicated in psychopathology, its role in anxiety-related disorders remains unclear. This retrospective study aimed to explore the characteristics and sleep parameters in patients with anxiety-related disorders and different sleep perception types, and to explore the associated factors for sleep misperception.

Methods

Patients with anxiety-related disorders who had complaint of insomnia for more than 3 months were collected at Wuhan Mental Health Center between December 2019 and July 2021. Patients underwent a two-night PSG monitoring and completed a self-reported sleep questionnaire. Behaviors were assessed using 30-item Nurses' Observation Scale for Inpatient Evaluation (NOSIE-30). Patients were divided into normal sleep perception (NSP), positive sleep perception abnormality [PSPA; overestimation of total sleep time (TST) >60 min], and negative sleep perception abnormality (NSPA; underestimation of TST >60 min) groups. PSG indicators and NOSIE-30 scores were compared among groups using the one-way analysis of variance and the Kruskal-Wallis test. Multiple linear regression analysis was performed to determine the associated factors for misperception index.

Results

The subjective and objective TST were 5.5 ± 1.9 h and 6.4 ± 1.7 h in 305 patients, respectively. Sixty-nine (22.6%) had PSPA, 80 (26.2%) had NSP, and 156 (51.1%) had NSPA. Subjective TST and objective sleep parameters were significantly different among groups. No statistical differences in NOSIE-30 subscale and total scores were observed among groups. Sex, rapid eye movement (REM)/TST (%), sleep efficiency, number of awakenings, Non-rapid eye movement of stage 2 sleep (NREM)/TST (%), REM spontaneous arousal times, sleep latency, diagnosis, social competence, and manifest psychosis were associated with sleep misperception.

Conclusion

Sleep misperception is common in patients with anxiety-related disorders. Various sleep perception types have different PSG profiles, but similar personal and social behaviors. These data may be helpful to conduct personalized treatment.

Toward a multi-lingual diagnostic tool for the worldwide problem of sleep health: The French RU-SATED validation

INTRODUCTION

Sleep health is "a multidimensional pattern of sleep-wakefulness, adapted to individual, social, and environmental demands, that promotes physical and mental well-being". The RU-SATED is a short practical self-reported symptom scale that is a reliable valid tool for the rapid evaluation of sleep health. This study sought to examine the psychometric validity of the French version.

METHODS

We conducted an observational cross-sectional study. All professionals working in Bordeaux University Hospital were asked to answer an internet-based questionnaire assessing sleep, mental and physical health outcomes. Sleep health was measured using the French RU-SATED scale obtained by a rigorous reverse translation process. Psychometric validity included factor structure, internal structural validity, concurrent validity and external validity of the measure, with sleep, mental and physical health outcomes.

RESULTS

A total of 1,562 participants were included with 80.5% of women and a mean age of 40.0 (±11.2). Sleep health was within the average range (M = 8.2, SD = 2.4) on the RU-SATED. Confirmatory factor analyses showed acceptable model fit measures. Cronbach's alpha coefficient was 0.57 and ranged from 0.46 to 0.58 when removing each item. The correlation between items with the overall corrected scores ranged from 0.19 to 0.43. The "Efficiency" item showed poor psychometric properties. Most items were highly correlated with their appropriate sleep outcome. All items showed a strong association with positive mental and physical health outcomes.

DISCUSSION

The French RU-SATED scale is a reliable valid tool for measuring sleep health in adults. Nevertheless, future studies should better evaluate the reliability and validity of the "Efficiency" item. It is also important to explore how the RU-SATED can be used to evaluate the impact of sleep hygiene strategies in promoting public health in accordance with models of sleep behavior change.

Changes in sleep structure and sleep spindles are associated with the neuropsychiatric profile in paradoxical insomnia

AIM

Sleep spindles have an important role in the pathophysiology and perception of sleep. We aimed to investigate the link between sleep spindles and microstructural architecture of sleep in regard to psychiatric characteristics in paradoxical insomnia.

METHOD

A total of 40 participants (20 with paradoxical insomnia, 20 healthy controls) were included in the study. All participants were evaluated by somnologists and undergone a full-night polysomnography at sleep laboratory. In addition, psychiatric interview was made by the same psychiatrist, and questionnaires were performed to assess the dimensions of the personality such as the neuroticism or extroversion (Eysenck Personality Questionnaire, EPQR-A); to evaluate the tendency to exaggerate somatic perceptions (Somatosensory Amplification Scale, SSAS), somatic parts of dissociation (Somatoform Dissociation Questionnaire, SDQ-20), and somatization (Somatization Scale, SS); to measure participants' feelings about their health and disease anxiety (Health Anxiety Inventory, HAI-18), and the level of uncontrollable and persistent anxiety (Penn State Worry Questionnaire, PSWQ); to investigate the tendency to ruminative thinking (Ruminative Thought Style Questionnaire, RTSQ), alexithymia (Toronto Alexithymia Scale, TAS-20); and to define the presence and the severity of depressive symptoms (Beck Depression Inventory, BDI).

RESULTS

The duration and frequency of the sleep spindles were similar between two groups, while the density was significantly decreased in paradoxical insomnia. The duration of sleep spindles, on the other hand, showed positive correlations with the extroversion dimension scores of EPQR-A and PSWQ scores.

DISCUSSION

Sleep protective mechanisms are disturbed in paradoxical insomnia as shown by the lower density of sleep spindles. In addition, fast spindle activity is associated with the personality traits, characterized by an increase in the expression of feelings and the level of anxiety.

The effect of COVID-19 lockdowns on sleep time perception: Comparing actigraphy and sleep diary measures

COVID-19 has become a long-term problem, and global pandemic conditions may persist for years. Researchers are providing mounting evidence of relationships between COVID-19 lockdowns and sleep problems. However, few studies have investigated the impact of home isolation on sleep time perception, especially in comparable social isolation situations with similar pressures. Subjective sleep time perception parameters were derived from sleep diaries. Objective parameters were derived from actigraphy. Subjective and objective data were obtained between February 17 and February 27, 2020 from 70 adult participants subject to COVID-19 related lockdown provisions in China. We divided participants into a home stayers (HS) group (subject to full stay-at home orders) and an area-restricted workers (ARW) group (permitted to work at their nearby workplaces). The HS group demonstrated significantly delayed actigraphy-defined sleep onset time compared to self-reported sleep onset time; this effect was absent in the ARW group. Between-group differences in actigraphy-defined sleep onset time and significant between-group differences for actigraphy-defined and self-reported wake-up time were observed. HS group participants also presented significantly delayed actigraphy-defined wake-up time compared with self-reported wake-up time. No significant effect was found on total sleep time perception. Moreover, sleep/wake time misperception were found to be associated with daylight exposure and physical activity levels respectively. To the extent they are generalizable, these results suggest that lockdown restrictions can affect sleep onset and wake-up time perception but not total sleep time perception. Public health policy should consider such effects in the present pandemic situation and in future emergent public health situations.

Sleep Disorder and Heart Failure with Preserved Ejection Fraction

It is generally considered that obstructive sleep apnea is a potential cause of heart failure (HF), and insomnia and central sleep apnea are results of HF. However, the number of reports describing the bidirectional relationship between sleep disorder and HF has increased. Sleep disorder may contribute to left ventricular diastolic dysfunction via left atrial overload, left ventricular remodeling, pulmonary hypertension, and atrial fibrillation, which lead to HF with preserved left ventricular ejection fraction. Overnight rostral fluid shift and lung congestion may lead to airflow obstruction in the upper pharynx and stimulate pulmonary irritant receptors, which induce hyperventilation and sleep disorder.

Concordance between self-reported and actigraphy-assessed sleep duration among African-American adults: findings from the Jackson Heart Sleep Study

STUDY OBJECTIVES

Most epidemiological studies assess sleep duration using questionnaires. Interpreting this information requires understanding the extent to which self-reported habitual sleep reflects objectively assessed sleep duration, particularly among African Americans, who disproportionately experience poor sleep health.

METHODS

Among African-American participants of the Jackson Heart Sleep Study, we investigated differences in questionnaire-based self-assessed average sleep duration and self-assessed wake-bed time differences compared to actigraphy-based assessments of total sleep time (TST) and average time in bed (TIB). Linear regression models provided estimates of concordance between actigraphy-based and self-reported sleep duration.

RESULTS

Among 821 adults, self-assessed average sleep duration was lower than self-assessed wake-bed time differences (6.4 ± 1.4 vs. 7.5 ± 1.7 h, p < 0.0001). Mean actigraphy-based TST was 6.6 ± 1.2 h, and actigraphy-based average TIB was 7.6 ± 1.2 h. Self-assessed average sleep duration and actigraphy-based TST were moderately correlated (r = 0.28, p < 0.0001). Self-assessed average sleep duration underestimated actigraphy-based TST by -30.7 min (95% confidence intervals [CI]: -36.5 to -24.9). In contrast, self-assessed wake-bed time differences overestimated actigraphy-based TST by 45.1 min (95% CI: 38.6-51.5). In subgroup analyses, self-assessed average sleep duration underestimated actigraphy-based measures most strongly among participants with insomnia symptoms.

CONCLUSIONS

Among African Americans, self-assessed average sleep duration underestimated objectively measured sleep while self-assessed wake-bed time differences overestimated objectively measured sleep. Sleep measurement property differences should be considered when investigating disparities in sleep and evaluating their associations with health outcomes.

Modeling sleep onset misperception in insomnia

OBJECTIVES

To extend and validate a previously suggested model of the influence of uninterrupted sleep bouts on sleep onset misperception in a large independent data set.

METHODS

Polysomnograms and sleep diaries of 139 insomnia patients and 92 controls were included. We modeled subjective sleep onset as the start of the first uninterrupted sleep fragment longer than Ls minutes, where parameter Ls reflects the minimum length of a sleep fragment required to be perceived as sleep. We compared the so-defined sleep onset latency (SOL) for various values of Ls. Model parameters were compared between groups, and across insomnia subgroups with respect to sleep onset misperception, medication use, age, and sex. Next, we extended the model to incorporate the length of wake fragments. Model performance was assessed by calculating root mean square errors (RMSEs) of the difference between estimated and perceived SOL.

RESULTS

Participants with insomnia needed a median of 34 minutes of undisturbed sleep to perceive sleep onset, while healthy controls needed 22 minutes (Mann-Whitney U = 4426, p < 0.001). Similar statistically significant differences were found between sleep onset misperceivers and non-misperceivers (median 40 vs. 20 minutes, Mann-Whitney U = 984.5, p < 0.001). Model outcomes were similar across other subgroups. Extended models including wake bout lengths resulted in only marginal improvements of model outcome.

CONCLUSIONS

Patients with insomnia, particularly sleep misperceivers, need larger continuous sleep bouts to perceive sleep onset. The modeling approach yields a parameter for which we coin the term Sleep Fragment Perception Index, providing a useful measure to further characterize sleep state misperception.

Misperception of sleep duration in mild traumatic brain injury/concussion: a preliminary report

Background: Polysomnographic (PSG) findings of persons with mild traumatic brain injury (mTBI)/concussion show longer total sleep time than patients themselves report; the reason for this is not entirely clear.Objective: This study aimed to elucidate the socio-demographic, brain-injury-related, and clinical characteristics that underlie accuracy of sleep duration reporting in mTBI/concussion.Methods: Thirty-seven participants diagnosed with mTBI/concussion (57% male, 47.54 ± 11.3 years old) underwent clinical and neuroimaging examinations, full-night PSG, and estimated sleep duration following PSG.Results: Mean self-reported sleep duration was 342 ± 93.6 minutes and PSG-measured sleep duration was 382 ± 76.8 minutes. Measurements were moderately correlated (rho = 0.46, p = .004). Age associated with self- and PSG-measured sleep duration (rho = 0.34 and rho = 0.84, respectively, p < .05). Self-reported sleep duration was uniquely associated with insomnia severity (rho = -0.48, p = .002). In the fully adjusted multivariable regression analysis, several clinical characteristics of patients explained 30% of the discrepancy between self- and PSG-measured sleep duration.Conclusion: The observed results indicate that persons with mTBI do not accurately assess their sleep duration and, therefore, PSG is warranted in clinical situations where sleep duration is of concern.

Brain reactivity using fMRI to insomnia stimuli in insomnia patients with discrepancy between subjective and objective sleep

Subjective–objective discrepancy of sleep (SODS) might be related to the distorted perception of sleep deficit and hypersensitivity to insomnia-related stimuli. We investigated differences in brain activation to insomnia-related stimuli among insomnia patients with SODS (SODS group), insomnia patients without SODS (NOSODS group), and healthy controls (HC). Participants were evaluated for subjective and objective sleep using sleep diary and polysomnography. Functional magnetic resonance imaging was conducted during the presentation of insomnia-related (Ins), general anxiety-inducing (Gen), and neutral (Neu) stimuli. Brain reactivity to the contrast of Ins vs. Neu and Gen vs. Neu was compared among the SODS (n = 13), NOSODS (n = 15), and HC (n = 16) groups. In the SODS group compared to other groups, brain areas including the left fusiform, bilateral precuneus, right superior frontal gyrus, genu of corpus callosum, and bilateral anterior corona radiata showed significantly increased blood oxygen level dependent (BOLD) signal in the contrast of Ins vs. Neu. There was no brain region with significantly increased BOLD signal in the Gen vs. Neu contrast in the group comparisons. Increased brain activity to insomnia-related stimuli in several brain regions of the SODS group is likely due to these individuals being more sensitive to sleep-related threat and negative cognitive distortion toward insomnia.

Sleep Discrepancy in a Randomized Controlled Trial of Brief Behavioral Therapy for Chronic Insomnia in Older Adults

Background/Objective: Some older adults with insomnia experience sleep discrepancy, often characterized by greater subjective sleep difficulties and shorter subjective sleep duration than the estimates derived from objective measures. The present study examined whether a brief behavioral therapy for insomnia (BBTi) is efficacious for reducing sleep discrepancy in older adults. Methods: This study is a secondary analysis of a randomized controlled trial of BBTi for community dwelling older adults with chronic insomnia (N = 62). Thirty-two participants received BBTi, delivered in four individual face-to-face sessions. Thirty received the self-monitoring control (SMC). They all completed daily sleep diaries and wore an actigraph from baseline to posttreatment, and for 2 weeks at 3-month follow-up. Sleep discrepancy was calculated by subtracting diary from actigraphy estimates of sleep onset latency (SOL), wake after sleep onset (WASO), and total sleep time (TST). Mixed modeling was used to analyze data. SOL discrepancy decreased significantly in BBTi participants compared to SMC participants. The decreases in SOL discrepancy were explained by changes in diary-assessed SOL and subjective sleep quality but not changes in actigraphy-assessed SOL. Although WASO discrepancy and TST discrepancy decreased from baseline to posttreatment and follow-up, the Time by Group interaction effects were not significant indicating that BBTi participants did not experience greater reductions in WASO discrepancy and TST discrepancy than SMC participants. In conclusion, BBTi is efficacious for reducing SOL discrepancy in older adults with chronic insomnia.

Psychosocial factors affecting sleep misperception in middle-aged community-dwelling adults

Sleep misperception has long been a major issue in the field of insomnia research. Most studies of sleep misperception examine sleep underestimation by comparing the results of polysomnography conducted in a laboratory environment with patients' sleep diary entries. We aimed to investigate psychosocial characteristics of adults who underestimated or overestimated sleep time in a nonclinical, middle-aged community-dwelling population. We collected one week of sleep data with wrist-worn accelerometers. We used egocentric social network analysis to analyze the effects of psychosocial factors. Among 4,060 study participants, 922 completed the accelerometer substudy. Underestimation was defined as an accelerometer-measured sleep time ≥ 6 h and a subjective sleep time < 6 h. Overestimation was defined as an objective sleep time < 6 h and a subjective sleep time ≥ 6 h. Psychosocial characteristics of the sleep misperception group were evaluated using multivariate regression analysis. A total of 47 participants underestimated sleep time, and 420 overestimated sleep time. Regression analysis revealed that women, living with spouse, economic satisfaction, and bridging potential had protective effects against sleep underestimation. Blame from a spouse involved a 3.8-times higher risk of underestimation than the control group (p = 0.002). In men, discussing concerns with a spouse had a protective effect against underestimation (p < 0.001). Economic satisfaction, feeling social network-based intimacy, and support from a spouse were associated with overestimation in women. In men, feeling social network-based intimacy was also associated with overestimation (p < 0.001). We found that social relationship quality was related to sleep overestimation and underestimation. This association was marked in women. Good social relationships may have positive effects on sleep misperception via attenuation of negative emotional reactions and effects on emotional regulation.

Altered thalamic connectivity in insomnia disorder during wakefulness and sleep

Insomnia disorder is the most common sleep disorder and has drawn increasing attention. Many studies have shown that hyperarousal plays a key role in the pathophysiology of insomnia disorder. However, the specific brain mechanisms underlying insomnia disorder remain unclear. To elucidate the neuropathophysiology of insomnia disorder, we investigated the brain functional networks of patients with insomnia disorder and healthy controls across the sleep–wake cycle. EEG‐fMRI data from 33 patients with insomnia disorder and 31 well‐matched healthy controls during wakefulness and nonrapid eye movement sleep, including N1, N2 and N3 stages, were analyzed. A medial and anterior thalamic region was selected as the seed considering its role in sleep–wake regulation. The functional connectivity between the thalamic seed and voxels across the brain was calculated. ANOVA with factors “group” and “stage” was performed on thalamus‐based functional connectivity. Correlations between the misperception index and altered functional connectivity were explored. A group‐by‐stage interaction was observed at widespread cortical regions. Regarding the main effect of group, patients with insomnia disorder demonstrated decreased thalamic connectivity with the left amygdala, parahippocampal gyrus, putamen, pallidum and hippocampus across wakefulness and all three nonrapid eye movement sleep stages. The thalamic connectivity in the subcortical cluster and the right temporal cluster in N1 was significantly correlated with the misperception index. This study demonstrated the brain functional basis in insomnia disorder and illustrated its relationship with sleep misperception, shedding new light on the brain mechanisms of insomnia disorder and indicating potential therapeutic targets for its treatment.

Analysis of Clinical Characteristics and Polysomnography Indicators of Obstructive Sleep Apnea-Hypopnea Syndrome Patients Based on Sleep Perception Types

Purpose: The aim of this study was to explore the clinical characteristics of different sleep perception types of obstructive sleep apnea-hypopnea syndrome (OSAHS) patients and to analyze the correlation between sleep perception and polysomnography (PSG) indicators in OSAHS patients. Methods: We retrospectively analyzed 355 patients diagnosed with OSAHS by PSG at the Sleep Medicine Center of Shengjing Hospital of China Medical University. Patients saw a doctor due to snoring and daytime sleepiness from March 2017 to March 2018. We excluded the patients who are <18 years old, had a history of OSAHS treatment, had other sleep and psychiatric disorders, and could not provide complete data. According to the patients' explanation, medical history, PSG indicators, and morning questionnaire after PSG, the patients were divided into normal sleep perception (NSP), positive sleep perception abnormality (PSPA), and negative sleep perception abnormality (NSPA). We analyze the demographic characteristics and PSG of the three groups with ANOVA and non-parametric tests. In addition, we conducted correlation analysis between sleep perception and PSG indicators. Results: Of OSAHS patient, 55.5% had sleep perception abnormalities, of which 35.5% were positive-perception abnormalities and 20% were negative-perception abnormalities. From the analysis of PSG indicators, the sleep perception abnormality was related to the frequency of spontaneous arousal of the patient (P = 0.003) and was not related to the slight arousal caused by respiratory events, oxygen desaturations, and limb movement events. OSAHS patients with PSPA had a higher oxygen desaturation index (P = 0.046) but no significant difference in post hoc test. PSPA group had significantly lower rapid eye movement (REM) latency and sleep efficiency and more wake after sleep onset (WASO) than had the other sleep perception groups. Multivariate linear regression analyses after adjusting for age and sex revealed that sleep perception was related to lowest oxygen saturation (LSaO2), TS90%, sleep efficiency, and WASO. Conclusion: Sleep perception abnormality is common in OSAHS patients. OSAHS patients with different sleep perception types have different PSG profiles. The OSAHS patients with PSPA have more severe hypoxia levels at night that require timely personalized treatment.

Electroencephalographic changes associated with subjective under- and overestimation of sleep duration

Feeling awake although sleep recordings indicate clear-cut sleep sometimes occurs in good sleepers and to an extreme degree in patients with so-called paradoxical insomnia. It is unknown what underlies sleep misperception, as standard polysomnographic (PSG) parameters are often normal in these cases. Here we asked whether regional changes in brain activity could account for the mismatch between objective and subjective total sleep times (TST). To set cutoffs and define the norm, we first evaluated sleep perception in a population-based sample, consisting of 2,092 individuals who underwent a full PSG at home and estimated TST the next day. We then compared participants with a low mismatch (normoestimators, n = 1,147, ±0.5 SD of mean) with those who severely underestimated (n = 52, &lt;2.5th percentile) or overestimated TST (n = 53, &gt;97.5th percentile). Compared with normoestimators, underestimators displayed higher electroencephalographic (EEG) activation (beta/delta power ratio) in both rapid eye movement (REM) and non-rapid eye movement (NREM) sleep, while overestimators showed lower EEG activation (significant in REM sleep). To spatially map these changes, we performed a second experiment, in which 24 healthy subjects and 10 insomnia patients underwent high-density sleep EEG recordings. Similarly to underestimators, patients displayed increased EEG activation during NREM sleep, which we localized to central-posterior brain areas. Our results indicate that a relative shift from low- to high-frequency spectral power in central-posterior brain regions, not readily apparent in conventional PSG parameters, is associated with underestimation of sleep duration. This challenges the concept of sleep misperception, and suggests that instead of misperceiving sleep, insomnia patients may correctly perceive subtle shifts toward wake-like brain activity.

Sleep onset (mis)perception in relation to sleep fragmentation, time estimation and pre-sleep arousal

Study objective

To elucidate the contribution of time estimation and pre sleep arousal to the component of sleep onset misperception not explained by sleep fragmentation.

Methods

At-home ambulatory polysomnograms (PSGs) of 31 people with insomnia were recorded. Participants performed a time estimation task and completed the Pre Sleep Arousal Scale (PSAS). Based on previous modelling of the relationship between objectively measured sleep fragmentation and sleep onset misperception, the subjective sleep onset was estimated for each participant as the start of the first uninterrupted sleep bout longer than 30 min. Subsequently, the component of misperception not explained by sleep fragmentation was calculated as the residual error between estimated sleep onset and perceived sleep onset. This residual error was correlated with individual time estimation task results and PSAS scores.

Results

A negative correlation between time estimation task results and the residual error of the sleep onset model was found, indicating that participants who overestimated a time interval during the day also overestimated their sleep onset latency (SOL). No correlation was found between PSAS scores and residual error.

Conclusions

Interindividual variations of sleep architecture possibly obscure the correlation of sleep onset misperception with time estimation and pre sleep arousal, especially in small groups. Therefore, we used a previously proposed model to account for the influence of sleep fragmentation. Results indicate that time estimation is associated with sleep onset misperception. Since sleep onset misperception appears to be a general characteristic of insomnia, understanding the underlying mechanisms is probably important for understanding and treating insomnia.

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Sleep onset misperception is probably a multifactorial process.

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We identify the part of misperception not explained by fragmentation.

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This metric was correlated with the time estimation and pre sleep arousal.

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Results indicate that time estimation is involved in sleep onset misperception.

Sleep continuity, stability and organization in good and bad sleepers

The relationship between objective and subjective sleep quality is still debated. Here, we investigate differences in objective sleep parameters in habitual subjective good sleepers and bad sleepers with the aim of evaluating sleep continuity, stability and organization as possible determinants of subjective sleep quality. In total, 38 subjects (good sleepers, N = 18; bad sleepers, N = 20) underwent two nights of sleep recording. Traditional sleep parameters displayed no between-groups differences. Conversely, bad sleepers showed lower sleep continuity (awakenings frequency), stability (e.g. arousals and state transitions frequency) and organization (e.g. number of sleep cycles and time spent in cycles). Our findings point to the involvement of these measures in determining habitual sleep quality perception and suggest the possibility to include them in standard sleep assessments.

CBT for late-life insomnia and the accuracy of sleep and wake perceptions: Results from a randomized-controlled trial

Subjective and objective estimates of sleep are often discordant among individuals with insomnia who typically under-report sleep time and over-report wake time at night. This study examined the impact and durability of cognitive-behavioural therapy for insomnia on improving the accuracy of sleep and wake perceptions in older adults, and tested whether changes in sleep quality were related to changes in the accuracy of sleep/wake perceptions. One-hundred and fifty-nine older veterans (97% male, mean age 72.2 years) who met diagnostic criteria for insomnia disorder were randomized to: (1) cognitive-behavioural therapy for insomnia (n = 106); or (2) attention control (n = 53). Assessments were conducted at baseline, post-treatment, 6-months and 12-months follow-up. Sleep measures included objective (via wrist actigraphy) and subjective (via self-report diary) total sleep time and total wake time, along with Pittsburgh Sleep Quality Index score. Discrepancy was computed as the difference between objective and subjective estimates of wake and sleep. Minutes of discrepancy were compared between groups across time, as were the relationships between Pittsburgh Sleep Quality Index scores and subsequent changes in discrepancy. Compared with controls, participants randomized to cognitive-behavioural therapy for insomnia became more accurate (i.e. minutes discrepancy was reduced) in their perceptions of sleep/wake at post-treatment, 6-months and 12-months follow-up (p < .05). Improved Pittsburgh Sleep Quality Index scores at each study assessment preceded and predicted reduced discrepancy at the next study assessment (p < .05). Cognitive-behavioural therapy for insomnia reduces sleep/wake discrepancy among older adults with insomnia. The reductions may be driven by improvements in sleep quality. Improving sleep quality appears to be a viable path to improving sleep perception and may contribute to the underlying effectiveness of cognitive-behavioural therapy for insomnia.

Data-Driven Analysis of EEG Reveals Concomitant Superficial Sleep During Deep Sleep in Insomnia Disorder

Study Objectives: The subjective suffering of people with Insomnia Disorder (ID) is insufficiently accounted for by traditional sleep classification, which presumes a strict sequential occurrence of global brain states. Recent studies challenged this presumption by showing concurrent sleep- and wake-type neuronal activity. We hypothesized enhanced co-occurrence of diverging EEG vigilance signatures during sleep in ID.

Methods: Electroencephalography (EEG) in 55 cases with ID and 64 controls without sleep complaints was subjected to a Latent Dirichlet Allocation topic model describing each 30 s epoch as a mixture of six vigilance states called Topics (T), ranked from N3-related T1 and T2 to wakefulness-related T6. For each stable epoch we determined topic dominance (the probability of the most likely topic), topic co-occurrence (the probability of the remaining topics), and epoch-to-epoch transition probabilities.

Results: In stable epochs where the N1-related T4 was dominant, T4 was more dominant in ID than in controls, and patients showed an almost doubled co-occurrence of T4 during epochs where the N3-related T1 was dominant. Furthermore, patients had a higher probability of switching from T1- to T4-dominated epochs, at the cost of switching to N3-related T2-dominated epochs, and a higher probability of switching from N2-related T3- to wakefulness-related T6-dominated epochs.

Conclusion: Even during their deepest sleep, the EEG of people with ID express more N1-related vigilance signatures than good sleepers do. People with ID are moreover more likely to switch from deep to light sleep and from N2 sleep to wakefulness. The findings suggest that hyperarousal never rests in ID.

Sleep EEG characteristics associated with sleep onset misperception

STUDY OBJECTIVE

To study sleep EEG characteristics associated with misperception of Sleep Onset Latency (SOL).

METHODS

Data analysis was based on secondary analysis of standard in-lab polysomnographic recordings in 20 elderly people with insomnia and 21 elderly good sleepers. Parameters indicating sleep fragmentation, such as number of awakenings, wake after sleep onset (WASO) and percentage of NREM1 were extracted from the polsysomnogram, as well as spectral power, microarousals and sleep spindle index. The correlation between these parameters during the first sleep cycle and the amount of misperceived sleep was assessed in the insomnia group. Additionally, we made a model of the minimum duration that a sleep fragment at sleep onset should have in order to be perceived as sleep, and we fitted this model to subjective SOLs of both subject groups.

RESULTS

Misperception of SOL was associated with increased percentage of NREM1 and more WASO during sleep cycle 1. For insomnia subjects, the best fit of modelled SOL with subjective SOL was found when assuming that sleep fragments shorter than 30 min at sleep onset were perceived as wake. The model indicated that healthy subjects are less sensitive to sleep interruptions and perceive fragments of 10 min or longer as sleep.

CONCLUSIONS

Our findings suggest that sleep onset misperception is related to sleep fragmentation at the beginning of the night. Moreover, we show that people with insomnia needed a longer duration of continuous sleep for the perception as such compared to controls. Further expanding the model could provide more detailed information about the underlying mechanisms of sleep misperception.

EEG spectral analysis of NREM sleep in a large sample of patients with insomnia and good sleepers: effects of age, sex and part of the night

Previous studies of the differences between patients with insomnia and good sleepers with regard to quantitative electroencephalographic measures have mostly utilized small samples and consequently had limited ability to account for potentially important confounding factors of age, sex and part of the night. We conducted a power spectral analysis using a large database of sleep electroencephalographic recordings to evaluate differences between patients with insomnia (N = 803) and good sleepers (N = 811), while simultaneously accounting for these factors and their interaction. Comparisons of power as a function of age and part of the night were made between cohorts (patients with insomnia versus good sleepers) by sex. Absolute power in the delta, theta and sigma bands declined with age for both females and males. Females had significantly greater power than males at all ages, and for each band, cohort and part of the night. These sex differences were much greater than differences between patients with insomnia and good sleepers. Compared with good sleepers, patients with insomnia under age 40-45 years had reduced delta band power during Part 1 of the night. Females with insomnia over age 45 years had increased delta and theta band power in Parts 2 and 3 of the night, and males with insomnia under age 40 years had reduced theta power in Part 1. Females with insomnia had increased beta2 power in all parts of the night, and males with insomnia had reduced alpha power during all parts of the night. Relative power (the proportion that an individual frequency band contributes to the total power) decreased in the delta band and increased in all other bands with age for both cohorts, sexes and all parts of the night. This analysis provides a unique resource for quantitative information on the differences in power spectra between patients with insomnia and good sleepers accounting for age, sex and part of the night.

Sleep Spindles Characteristics in Insomnia Sufferers and Their Relationship with Sleep Misperception

Cortical hyperarousal is higher in insomnia sufferers (INS) than in good sleepers (GS) and could be related to an alteration in sleep protection mechanisms, like reduced density or altered characteristics in sleep spindles. The deficient sleep protection mechanisms might in turn enhance underestimation of sleep. This study's objective was to document sleep spindles characteristics in INS compared with GS and to investigate their potential role in sleep consolidation and misperception. Seventeen individuals with paradoxical insomnia (PARA-I), 24 individuals with psychophysiological insomnia (PSY-I), and 29 GS completed four consecutive polysomnographic nights in laboratory. Sleep spindles were detected automatically during stage 2 and SWS (3-4) on night 3. Number, density, duration, frequency, and amplitude of sleep spindles were calculated. A misperception index was used to determine the degree of discrepancy between subjective and objective total sleep times. Kruskal-Wallis H tests and post hoc tests revealed that PARA-I had significantly shorter sleep spindles than GS but that PSY-I and GS did not differ on spindles length. A standard multiple regression model revealed that neither sleep spindles characteristics nor objective sleep measures were predictive of sleep misperception. A longer duration of spindles could reflect a higher gating process but this hypothesis still needs to be confirmed in replication studies.