An online behavioural self-help intervention rapidly improves acute insomnia severity and subjective mood during the COVID-19 pandemic: a stratified randomised controlled trial

STUDY OBJECTIVES

Stressful life events, such as the COVID-19 pandemic, can cause acute insomnia. Cognitive behavioural therapy for acute insomnia is effective but is both time and resource-intensive. This study investigated if an online behavioural self-help intervention, which has been successfully used alongside sleep restriction for acute insomnia, reduced insomnia severity and improved mood in acute insomnia. This study also assessed good sleepers to explore if a "sleep vaccination" approach was feasible.

METHODS

In this online stratified randomised controlled trial, 344 participants (103 good sleepers and 241 participants with DSM-5 acute insomnia) were randomised to receive the intervention/no intervention (good sleepers) or intervention/intervention after 28 days (poor sleepers). Insomnia severity was assessed using the ISI (primary outcome), and anxiety and depression using the GAD-7/PHQ-9 (secondary outcomes) at baseline, one week, one month and three-month follow-up.

RESULTS

In people with acute insomnia, relative to baseline, there were significant reductions in ISI (dz = 1.17), GAD-7 (dz = .70) and PHQ-9 (dz = .60) scores at one week follow-up. ISI, GAD-7 and PHQ-9 scores were significantly lower at all follow-up time points, relative to baseline. Subjective diary-derived sleep continuity was unaffected. No beneficial effects upon sleep or mood were observed in good sleepers.

CONCLUSIONS

An online behavioural self-help intervention rapidly reduces acute insomnia severity (within one week), and benefits mood in people with acute insomnia. These beneficial effects are maintained up to three months later. Although the use of the intervention is feasible in good sleepers, their subjective sleep was unaffected.

Genome-wide association analysis of composite sleep health scores in 413,904 individuals

Recent genome-wide association studies (GWASs) of several individual sleep traits have identified hundreds of genetic loci, suggesting diverse mechanisms. Moreover, sleep traits are moderately correlated, and together may provide a more complete picture of sleep health, while also illuminating distinct domains. Here we construct novel sleep health scores (SHSs) incorporating five core self-report measures: sleep duration, insomnia symptoms, chronotype, snoring, and daytime sleepiness, using additive (SHS-ADD) and five principal components-based (SHS-PCs) approaches. GWASs of these six SHSs identify 28 significant novel loci adjusting for multiple testing on six traits (p<8.3e-9), along with 341 previously reported loci (p<5e-08). The heritability of the first three SHS-PCs equals or exceeds that of SHS-ADD (SNP-h2=0.094), while revealing sleep-domain-specific genetic discoveries. Significant loci enrich in multiple brain tissues and in metabolic and neuronal pathways. Post GWAS analyses uncover novel genetic mechanisms underlying sleep health and reveal connections to behavioral, psychological, and cardiometabolic traits.

Towards the neurobiology of insomnia: A systematic review of neuroimaging studies

Insomnia disorder signifies a major public health concern. The development of neuroimaging techniques has permitted to investigate brain mechanisms at a structural and functional level. The present systematic review aims at shedding light on functional, structural, and metabolic substrates of insomnia disorder by integrating the available published neuroimaging data. The databases PubMed, PsycARTICLES, PsycINFO, CINAHL and Web of Science were searched for case-control studies comparing neuroimaging data from insomnia patients and healthy controls. 85 articles were judged as eligible. For every observed finding of each study, the effect size was calculated from standardised mean differences, statistic parameters and figures, showing a marked heterogeneity that precluded a comprehensive quantitative analysis. From a qualitative point of view, considering the findings of significant group differences in the reported regions across the articles, this review highlights the major involvement of the anterior cingulate cortex, thalamus, insula, precuneus and middle frontal gyrus, thus supporting some central themes in the debate on the neurobiology of and offering interesting insights into the psychophysiology of sleep in this disorder.

Causal Association Between Subtypes of Excessive Daytime Sleepiness and Risk of Cardiovascular Diseases

BACKGROUND

Excessive daytime sleepiness (EDS), experienced in 10% to 20% of the population, has been associated with cardiovascular disease and death. However, the condition is heterogeneous and is prevalent in individuals having short and long sleep duration. We sought to clarify the relationship between sleep duration subtypes of EDS with cardiovascular outcomes, accounting for these subtypes.

METHODS AND RESULTS

We defined 3 sleep duration subtypes of excessive daytime sleepiness: normal (6-9 hours), short (<6 hours), and long (>9 hours), and compared these with a nonsleepy, normal-sleep-duration reference group. We analyzed their associations with incident myocardial infarction (MI) and stroke using medical records of 355 901 UK Biobank participants and performed 2-sample Mendelian randomization for each outcome. Compared with healthy sleep, long-sleep EDS was associated with an 83% increased rate of MI (hazard ratio, 1.83 [95% CI, 1.21-2.77]) during 8.2-year median follow-up, adjusting for multiple health and sociodemographic factors. Mendelian randomization analysis provided supporting evidence of a causal role for a genetic long-sleep EDS subtype in MI (inverse-variance weighted β=1.995, P=0.001). In contrast, we did not find evidence that other subtypes of EDS were associated with incident MI or any associations with stroke (P>0.05).

CONCLUSIONS

Our study suggests the previous evidence linking EDS with increased cardiovascular disease risk may be primarily driven by the effect of its long-sleep subtype on higher risk of MI. Underlying mechanisms remain to be investigated but may involve sleep irregularity and circadian disruption, suggesting a need for novel interventions in this population.

The European Insomnia Guideline: An update on the diagnosis and treatment of insomnia 2023

Progress in the field of insomnia since 2017 necessitated this update of the European Insomnia Guideline. Recommendations for the diagnostic procedure for insomnia and its comorbidities are: clinical interview (encompassing sleep and medical history); the use of sleep questionnaires and diaries (and physical examination and additional measures where indicated) (A). Actigraphy is not recommended for the routine evaluation of insomnia (C), but may be useful for differential-diagnostic purposes (A). Polysomnography should be used to evaluate other sleep disorders if suspected (i.e. periodic limb movement disorder, sleep-related breathing disorders, etc.), treatment-resistant insomnia (A) and for other indications (B). Cognitive-behavioural therapy for insomnia is recommended as the first-line treatment for chronic insomnia in adults of any age (including patients with comorbidities), either applied in-person or digitally (A). When cognitive-behavioural therapy for insomnia is not sufficiently effective, a pharmacological intervention can be offered (A). Benzodiazepines (A), benzodiazepine receptor agonists (A), daridorexant (A) and low-dose sedating antidepressants (B) can be used for the short-term treatment of insomnia (≤ 4 weeks). Longer-term treatment with these substances may be initiated in some cases, considering advantages and disadvantages (B). Orexin receptor antagonists can be used for periods of up to 3 months or longer in some cases (A). Prolonged-release melatonin can be used for up to 3 months in patients ≥ 55 years (B). Antihistaminergic drugs, antipsychotics, fast-release melatonin, ramelteon and phytotherapeutics are not recommended for insomnia treatment (A). Light therapy and exercise interventions may be useful as adjunct therapies to cognitive-behavioural therapy for insomnia (B).

Adherence to sleep restriction therapy - An evaluation of existing measures

Sleep restriction, a key element of cognitive behavioural therapy for insomnia, involves considerable behavioural changes in patients' lives, leading to side-effects like increased daytime sleepiness. Studies on sleep restriction rarely report adherence, and when assessed it is often limited to the average number of therapy sessions attended. This study aims to systematically evaluate different measures of adherence to cognitive behavioural therapy for insomnia and their relationship with treatment outcome. This is a secondary analysis of data from a randomized controlled trial investigating cognitive behavioural therapy for insomnia (Johann et al. (2020) Journal of Sleep Research, 29, e13102). The sample included 23 patients diagnosed with insomnia according to DSM-5 criteria who underwent 8 weeks of cognitive behavioural therapy for insomnia. The following adherence measures based on sleep diary data were used: number of sessions completed; deviations from agreed time in bed; average percentage of patients deviating from bedtime by 15, 30 or 60 min; variability of bedtime and wake-up time; change in time in bed from pre- to post-assessment. Treatment outcome was assessed using the Insomnia Severity Index. Multiple regression models were employed, and insomnia severity was controlled for. Results showed that none of the adherence measures predict insomnia severity. Baseline insomnia severity, dysfunctional thoughts and attitudes about sleep, depression or perfectionism did not predict adherence. The limited variance in the outcome parameter due to most patients benefiting from treatment and the small sample size may explain these findings. Additionally, using objective measures like actigraphy could provide a better understanding of adherence behaviour. Lastly, the presence of perfectionism in patients with insomnia may have mitigated adherence problems in this study.

The importance and limitations of polysomnography in insomnia disorder-a critical appraisal

The importance polysomnography (PSG) in the diagnosis and treatment process of insomnia disorder (ID) remains highly disputed. This review summarises the state of the science regarding PSG indications and findings in ID, and the indications to conduct PSG in ID as stated by relevant guidelines. It then highlights the most relevant questions regarding the topic, including the relevance of ID subtyping, to allow an individualised pharmacological or psychotherapeutic treatment approach.

The potential of biomarkers for diagnosing insomnia: Consensus statement of the WFSBP Task Force on Sleep Disorders

OBJECTIVES

Thus far, the diagnosis of insomnia is based on purely clinical criteria. Although a broad range of altered physiological parameters has been identified in insomniacs, the evidence to establish their diagnostic usefulness is very limited. Purpose of this WFSBP Task Force consensus paper is to systematically evaluate a series of biomarkers as potential diagnostic tools for insomnia.

METHODS

A newly created grading system was used for assessing the validity of various measurements in establishing the diagnosis of insomnia; these measurements originated from relevant studies selected and reviewed by experts.

RESULTS

The measurements with the highest diagnostic performance were those derived from psychometric instruments. Biological measurements which emerged as potentially useful diagnostic instruments were polysomnography-derived cyclic alternating pattern, actigraphy, and BDNF levels, followed by heart rate around sleep onset, deficient melatonin rhythm, and certain neuroimaging patterns (mainly for the activity of frontal and pre-frontal cortex, hippocampus and basal ganglia); yet, these findings need replication, as well as establishment of commonly accepted methodology and diagnostic cut-off points. Routine polysomnography, EEG spectral analysis, heart rate variability, skin conductance, thermoregulation, oxygen consumption, HPA axis, and inflammation indices were not shown to be of satisfactory diagnostic value.

CONCLUSIONS

Apart from psychometric instruments which are confirmed to be the gold standard in diagnosing insomnia, six biomarkers emerge as being potentially useful for this purpose.

Convergent abnormality in the subgenual anterior cingulate cortex in insomnia disorder: A revisited neuroimaging meta-analysis of 39 studies

The neurobiological underpinnings of insomnia disorder (ID) are still poorly understood. A previous meta-analysis conducted by our research group in 2018 revealed no consistent regional alterations based on the limited number of eligible studies. Given the number of studies published during the last few years, we revisited the meta-analysis to provide an update to the field. Following the best-practice guidelines for conducting neuroimaging meta-analyses, we searched several databases (PubMed, Web of Science, and BrainMap) and identified 39 eligible structural and functional studies, reporting coordinates reflecting significant group differences between ID patients and healthy controls. A significant convergent regional alteration in the subgenual anterior cingulate cortex (sgACC) was observed using the activation likelihood estimation algorithm. Behavioural decoding using the BrainMap database indicated that this region is involved in fear-related emotional and cognitive processing. The sgACC showed robust task-based co-activation in meta-analytic connectivity modelling and task-free functional connectivity in a resting-state functional connectivity analysis with the main hubs of the salience and default mode networks, including the posterior cingulate cortex and dorsal ACC, amygdala, hippocampus, and medial prefrontal cortex. Collectively, the findings from this large-scale meta-analysis suggest a critical role of the sgACC in the pathophysiology of ID.

Lack of structural brain alterations associated with insomnia: findings from the ENIGMA-Sleep Working Group

Existing neuroimaging studies have reported divergent structural alterations in insomnia disorder (ID). In the present study, we performed a large-scale coordinated meta-analysis by pooling structural brain measures from 1085 subjects (mean [SD] age 50.5 [13.9] years, 50.2% female, 17.4% with insomnia) across three international Enhancing NeuroImaging Genetics through Meta-Analysis (ENIGMA)-Sleep cohorts. Two sites recruited patients with ID/controls: Freiburg (University of Freiburg Medical Center, Freiburg, Germany) 42/43 and KUMS (Kermanshah University of Medical Sciences, Kermanshah, Iran) 42/49, while the Study of Health in Pomerania (SHIP-Trend, University Medicine Greifswald, Greifswald, Germany) recruited population-based individuals with/without insomnia symptoms 75/662. The influence of insomnia on magnetic resonance imaging-based brain morphometry using an insomnia brain score was then assessed. Within each cohort, we used an ordinary least-squares linear regression to investigate the link between the individual regional cortical and subcortical volumes and the presence of insomnia symptoms. Then, we performed a fixed-effects meta-analysis across cohorts based on the first-level results. For the insomnia brain score, weighted logistic ridge regression was performed on one sample (Freiburg), which separated patients with ID from controls to train a model based on the segmentation measurements. Afterward, the insomnia brain scores were validated using the other two samples. The model was used to predict the log-odds of the subjects with insomnia given individual insomnia-related brain atrophy. After adjusting for multiple comparisons, we did not detect any significant associations between insomnia symptoms and cortical or subcortical volumes, nor could we identify a global insomnia-related brain atrophy pattern. Thus, we observed inconsistent brain morphology differences between individuals with and without insomnia across three independent cohorts. Further large-scale cross-sectional/longitudinal studies using both structural and functional neuroimaging are warranted to decipher the neurobiology of insomnia.

World sleep society international sleep medicine guidelines position statement endorsement of "behavioral and psychological treatments for chronic insomnia disorder in adults: An American Academy of sleep medicine clinical practice guidelines"

This paper summarizes the position statement of the World Sleep Society (WSS) International Guidelines Committee regarding the Clinical Practice Guidelines on the Behavioral and Psychological Treatments for Chronic Insomnia Disorder in Adults prepared by a task force of the American Academy of Sleep Medicine (AASM). The practice guidelines were reviewed for their relevance and applicability to the practice of sleep medicine around the world. The WSS Work Group endorsed the AASM strong recommendation for Multicomponent Cognitive Behavioral Therapy as the treatment of choice for Insomnia Disorder and conditional endorsement for its single-therapy components (sleep restriction, stimulus control, relaxation); use of sleep hygiene education as single therapy was not endorsed due to lack of evidence for its efficacy. The strong recommendation for multicomponent CBT-I applied to patients with chronic insomnia disorder with or without comorbid psychiatric and medical conditions. Main caveats with regard to CBT-I remains the lack of adequately trained therapists and variability in terms of training available in different parts of the world. Unanswered questions about the applicability, availability, accessibility and potential sociodemographic (age, sex, ethnicity, regions) moderators of treatment outcomes were discussed. Despite growing evidence documenting the benefits of digital CBT-I, individual, in-person CBT-I delivered by a trained professional (mental health) provider is regarded as the optimal method to deliver CBT-I.

Associations between sleep health and grey matter volume in the UK Biobank cohort (n = 33 356)

As suggested by previous research, sleep health is assumed to be a key determinant of future morbidity and mortality. In line with this, recent studies have found that poor sleep is associated with impaired cognitive function. However, to date, little is known about brain structural abnormalities underlying this association. Although recent findings link sleep health deficits to specific alterations in grey matter volume, evidence remains inconsistent and reliant on small sample sizes. Addressing this problem, the current preregistered study investigated associations between sleep health and grey matter volume (139 imaging-derived phenotypes) in the UK Biobank cohort (33 356 participants). Drawing on a large sample size and consistent data acquisition, sleep duration, insomnia symptoms, daytime sleepiness, chronotype, sleep medication and sleep apnoea were examined. Our main analyses revealed that long sleep duration was systematically associated with larger grey matter volume of basal ganglia substructures. Insomnia symptoms, sleep medication and sleep apnoea were not associated with any of the 139 imaging-derived phenotypes. Short sleep duration, daytime sleepiness as well as late and early chronotype were associated with solitary imaging-derived phenotypes (no recognizable pattern, small effect sizes). To our knowledge, this is the largest study to test associations between sleep health and grey matter volume. Clinical implications of the association between long sleep duration and larger grey matter volume of basal ganglia are discussed. Insomnia symptoms as operationalized in the UK Biobank do not translate into grey matter volume findings.

Discriminating Paradoxical and Psychophysiological Insomnia Based on Structural and Functional Brain Images: A Preliminary Machine Learning Study

Insomnia disorder (ID) is a prevalent mental illness. Several behavioral and neuroimaging studies suggested that ID is a heterogenous condition with various subtypes. However, neurobiological alterations in different subtypes of ID are poorly understood. We aimed to assess whether unimodal and multimodal whole-brain neuroimaging measurements can discriminate two commonly described ID subtypes (i.e., paradoxical and psychophysiological insomnia) from each other and healthy subjects. We obtained T1-weighted images and resting-state fMRI from 34 patients with ID and 48 healthy controls. The outcome measures were grey matter volume, cortical thickness, amplitude of low-frequency fluctuation, degree centrality, and regional homogeneity. Subsequently, we applied support vector machines to classify subjects via unimodal and multimodal measures. The results of the multimodal classification were superior to those of unimodal approaches, i.e., we achieved 81% accuracy in separating psychophysiological vs. control, 87% for paradoxical vs. control, and 89% for paradoxical vs. psychophysiological insomnia. This preliminary study provides evidence that structural and functional brain data can help to distinguish two common subtypes of ID from each other and healthy subjects. These initial findings may stimulate further research to identify the underlying mechanism of each subtype and develop personalized treatments for ID in the future.

Sleep health dimensions and shift work as longitudinal predictors of cognitive performance in the UK Biobank cohort

STUDY OBJECTIVES

The long-term effects of sleep health and shift work on cognitive performance are unclear. In addition, research has been limited by small sample sizes and short follow-up periods. We conducted one of the largest examinations of the longitudinal influence of sleep health dimensions and shift work on cognitive performance in people of middle and old age using data from the UK Biobank. The hypothesis was that poor sleep health and shift work would predict lower cognitive performance.

METHODS

Self-reported sleep duration, daytime sleepiness, insomnia symptoms, chronotype and shift work status were assessed as predictors at baseline. Cognitive performance was operationalised by a touchscreen test battery at follow-up between 7.4 ± 2.2 and 9.0 ± 0.9 years after baseline assessment, depending on the specific task. Models were performed for each cognitive domain including relevant confounders (e.g., depression). The alpha level was set at p<0.01 for all analyses.

RESULTS

The study sample comprised 9,394 participants for the reasoning task, 30,072 for the reaction time task, 30,236 for the visual memory task, 2,019 for the numeric memory task and 9,476 for the prospective memory task. Shift work without night shifts (ß= -2.0x10- 1 ± 6.5x10- 2, p=0.002) and with night shifts (ß= -1.9x10- 1 ± 7.2x10- 2, p=0.010) predicted a significantly reduced performance in the reasoning task. Short sleep duration (ß= -2.4x10- 1 ± 7.9x10- 2, p=0.003) and shift work without night shifts (ß= -3.9x10- 1 ± 1.2x10- 1, p=0.002) predicted a significantly lower performance in the task probing prospective memory.

CONCLUSIONS

Our results suggest that, after controlling for confounding variables, shift work and short sleep duration are important predictors for cognitive performance in people of middle and old age. Further work is required to examine causal mechanisms of the observed associations.

Associations between insomnia symptoms and functional connectivity in the UK Biobank cohort (n = 29,423)

An increasing number of studies harness resting-state fMRI functional connectivity analysis to investigate the neurobiological mechanisms of insomnia. The results to date are inconsistent and the detection of minor and widely distributed alterations in functional connectivity requires large sample sizes. The present study investigated associations between insomnia symptoms and resting-state functional connectivity at the whole-brain level in the largest sample to date. This cross-sectional analysis used resting-state imaging data from the UK Biobank, a large scale, population-based biomedical database. The analysis included 29,423 participants (age: 63.1 ± 7.5 years, 54.3% female), comprising 9210 with frequent insomnia symptoms and 20,213 controls without. Linear models were adjusted for relevant clinical, imaging, and socio-demographic variables. The Akaike information criterion was used for model selection. Multiple comparisons were corrected using the false discovery rate with a significance level of q < 0.05. Frequent insomnia symptoms were associated with increased connectivity within the default mode network and frontoparietal network, increased negative connectivity between the default mode network and the frontoparietal network, and decreased connectivity between the salience network and a node of the default mode network. Furthermore, frequent insomnia symptoms were associated with altered functional connectivity between nodes comprising sensory areas and the cerebellum. These functional alterations of brain networks may underlie dysfunctional affective and cognitive processing in insomnia and contribute to subjectively and objectively impaired sleep. However, it must be noted that the item that was used to assess frequent insomnia symptoms in this study did not assess all the characteristics of clinically diagnosed insomnia.

How many hours do you sleep? A comparison of subjective and objective sleep duration measures in a sample of insomnia patients and good sleepers

Our objective was to assess the agreement and linear relationships amongst multiple measures of sleep duration in a sample of patients with insomnia disorder and good sleeper controls. We retrospectively analysed data from 123 patients with insomnia disorder and 123 age- and gender-matched good sleeper controls who completed a simple subjective habitual sleep duration question (Pittsburgh Sleep Quality Index), a sleep diary (5-14 days), 2 nights of polysomnography, and two corresponding morning subjective estimates of sleep duration. Descriptive statistics, linear regression analyses and Bland-Altman plots were used to describe the relationship and (dis)agreement between sleep duration measures. Relationships between polysomnography and the simple question as well as between polysomnography and sleep diary were weak to non-existent. Subjective measures and polysomnography did not agree. Sleep duration measured with the Pittsburgh Sleep Quality Index or sleep diary was about 2 hr above or up to 4 hr below polysomnography-measured sleep duration. Patients with insomnia disorder, on average, reported shorter sleep duration compared with polysomnography, while good sleeper controls, on average, reported longer sleep duration compared with polysomnography. The results suggest that subjective and objective measures apparently capture different aspects of sleep, even when nominally addressing the same value (sleep duration). They disagree in both patients with insomnia disorder and good sleeper controls, but in different directions. Studies assessing sleep duration should take into account both the investigated population and the assessment method when interpreting results. Future studies should continue to investigate possible psychological and physiological correlates of sleep (mis)perception.

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.

The Effects of Cognitive Behavioral Therapy for Insomnia on Multidimensional Perfectionism

Perfectionism is related to insomnia and objective markers of disturbed sleep. This study examined whether multidimensional perfectionism is related to dysfunctional beliefs about sleep, sleep-effort, pre-sleep arousal, and polysomnography-determined markers of sleep among individuals with insomnia. The effects of cognitive behavioral therapy for insomnia (CBT-I) on perfectionism was also examined. This was a secondary analysis of a randomized controlled trial on CBT-I. Forty-three insomnia patients were randomized to treatment (receiving CBT-I) or waitlist control groups. Sleep was recorded using polysomnography at baseline. Participants completed measures of perfectionism, dysfunctional beliefs about sleep, sleep-effort and pre-sleep arousal at baseline and posttreatment. Total perfectionism scores and doubts about action, concern over mistakes and personal standards were each significantly related to increased sleep effort, pre-sleep arousal and dysfunctional beliefs about sleep at baseline. Patients receiving treatment displayed increased total perfectionism scores posttreatment d = .49. In those receiving treatment, levels of organization d = .49 and parental expectations d = .47 were significantly increased posttreatment, relative to baseline. In line with the literature, our results confirm that perfectionism is related to insomnia. Here, insomnia was related to increased sleep effort, pre-sleep arousal and dysfunctional beliefs about sleep. The propensity to maintain a high standard of order and organization may be elevated following CBT-I, considering the treatment protocol expects patients to strictly adhere to a set of clearly defined rules. Levels of parental expectations may be increased following CBT-I since the patient-therapist-relationship may trigger implicit expectations in patients which are reminiscent of their relationship to their parents.

On the relationship between EEG spectral analysis and pre-sleep cognitive arousal in insomnia disorder: towards an integrated model of cognitive and cortical arousal

According to the hyperarousal model, insomnia is characterised by increased arousal in the cortical, cognitive, and physiological domains. However, the interaction between these arousal domains is poorly understood. The present observational case-control study aimed to investigate cortical arousal during the night, pre-sleep cognitive arousal and the relationship between these two domains. A total of 109 patients with insomnia disorder (ID) and 109 age-and gender matched healthy controls were investigated on two sleep laboratory nights. Electroencephalographic (EEG) spectral power during non-rapid eye movement (NREM) and REM sleep was analysed as a measure of cortical arousal. In addition, patients completed the Pre-Sleep Arousal Scale (PSAS), which consists of two subscales, one for cognitive arousal (PSAS-CA) and one for self-reported somatic arousal (PSAS-SA). The relationship between the subscale scores and EEG spectral power was calculated by multi- and univariate analyses of variance. During NREM and REM sleep, patients with ID showed significantly increased spectral power in the EEG gamma band. In addition, patients with ID showed significantly increased scores on both subscales of the PSAS. The PSAS-CA score was significantly associated with increased NREM and REM gamma power, whereas PSAS-SA was associated with decreases in NREM and REM gamma power. Consistent with our hypothesis, patients with ID showed increased cortical and cognitive arousal. Moreover, there was an association between these two arousal domains, which may indicate that cortical arousal during the night is (at least in part) elicited by pre-sleep worry and rumination.

Help for insomnia from the app store? A standardized rating of mobile health applications claiming to target insomnia

A large number of mobile health applications claiming to target insomnia are available in commercial app stores. However, limited information on the quality of these mobile health applications exists. The present study aimed to systematically search the European Google Play and Apple App Store for mobile health applications targeting insomnia, and evaluate the quality, content, evidence base and potential therapeutic benefit. Eligible mobile health applications were evaluated by two independent reviewers using the Mobile Application Rating Scale-German, which ranges from 1 - inadequate to 5 - excellent. Of 2236 identified mobile health applications, 53 were included in this study. Most mobile health applications (68%) had a moderate overall quality. Concerning the four main subscales of the Mobile Application Rating Scale-German, functionality was rated highest (M = 4.01, SD = 0.52), followed by information quality (M = 3.49, SD = 0.72), aesthetics (M = 3.31, SD = 1.04) and engagement (M = 3.02, SD = 1.03). While scientific evidence was identified for 10 mobile health applications (19%), only one study employed a randomized controlled design. Fifty mobile health applications featured sleep hygiene/psychoeducation (94%), 27 cognitive therapy (51%), 26 relaxation methods (49%), 24 stimulus control (45%), 16 sleep restriction (30%) and 24 sleep diaries (45%). Mobile health applications may have the potential to improve the care of insomnia. Yet, data on the effectiveness of mobile health applications are scarce, and this study indicates a large variance in the quality of the mobile health applications. Thus, independent information platforms are needed to provide healthcare seekers and providers with reliable information on the quality and content of mobile health applications.

Comparative effectiveness of three versions of a stepped care model for insomnia differing in the amount of therapist support in internet-delivered treatment: study protocol for a pragmatic cluster randomised controlled trial (GET Sleep)

INTRODUCTION

It is unclear how internet-delivered cognitive-behavioural therapy for insomnia (CBT-I) can be integrated into healthcare systems, and little is known about the optimal level of therapist guidance. The aim of this study is to investigate three different versions of a stepped care model for insomnia (IG1, IG2, IG3) versus treatment as usual (TAU). IG1, IG2 and IG3 rely on treatment by general practitioners (GPs) in the entry level and differ in the amount of guidance by e-coaches in internet-delivered CBT-I.

METHODS AND ANALYSIS

In this randomised controlled trial, 4268 patients meeting International Classification of Diseases, Tenth Revision (ICD-10) criteria for insomnia will be recruited. The study will use cluster randomisation of GPs with an allocation ratio of 3:3:3:1 (IG1, IG2, IG3, TAU). In step 1 of the stepped care model, GPs will deliver psychoeducational treatment; in step 2, an internet-delivered CBT-I programme will be used; in step 3, GPs will refer patients to specialised treatment. Outcomes will be collected at baseline, and 4 weeks, 12 weeks and 6 months after baseline assessment. The primary outcome is insomnia severity at 6 months. An economic evaluation will be conducted and qualitative interviews will be used to explore barriers and facilitators of the stepped care model.

ETHICS AND DISSEMINATION

The study protocol was approved by the Ethics Committee of the Medical Centre-University of Freiburg. The results of the study will be published irrespective of the outcome.

TRIAL REGISTRATION NUMBER

DRKS00021503.

Insomnia disorder: State of the science and challenges for the future

Insomnia disorder comprises symptoms during night and day that strongly affect quality of life and wellbeing. Prolonged sleep latency, difficulties to maintain sleep and early morning wakening characterize sleep complaints, whereas fatigue, reduced attention, impaired cognitive functioning, irritability, anxiety and low mood are key daytime impairments. Insomnia disorder is well acknowledged in all relevant diagnostic systems: Diagnostic and Statistical Manual of the American Psychiatric Association, 5th revision, International Classification of Sleep Disorders, 3rd version, and International Classification of Diseases, 11th revision. Insomnia disorder as a chronic condition is frequent (up to 10% of the adult population, with a preponderance of females), and signifies an important and independent risk factor for physical and, especially, mental health. Insomnia disorder diagnosis primarily rests on self-report. Objective measures like actigraphy or polysomnography are not (yet) part of the routine diagnostic canon, but play an important role in research. Disease concepts of insomnia range from cognitive-behavioural models to (epi-) genetics and psychoneurobiological approaches. The latter is derived from knowledge about basic sleep-wake regulation and encompass theories like rapid eye movement sleep instability/restless rapid eye movement sleep. Cognitive-behavioural models of insomnia led to the conceptualization of cognitive-behavioural therapy for insomnia, which is now considered as first-line treatment for insomnia worldwide. Future research strategies will include the combination of experimental paradigms with neuroimaging and may benefit from more attention to dysfunctional overnight alleviation of distress in insomnia. With respect to therapy, cognitive-behavioural therapy for insomnia merits widespread implementation, and digital cognitive-behavioural therapy may assist delivery along treatment guidelines. However, given the still considerable proportion of patients responding insufficiently to cognitive-behavioural therapy for insomnia, fundamental studies are highly necessary to better understand the brain and behavioural mechanisms underlying insomnia. Mediators and moderators of treatment response/non-response and the associated development of tailored and novel interventions also require investigation. Recent studies suggest that treatment of insomnia may prove to add significantly as a preventive strategy to combat the global burden of mental disorders.

Engaging Refugees With a Culturally Adapted Digital Intervention to Improve Sleep: A Randomized Controlled Pilot Trial

Refugees are exposed to multiple stressors affecting their mental health. Given various barriers to mental healthcare in the arrival countries, innovative healthcare solutions are needed. One such solution could be to offer low-threshold treatments, for example by culturally adapting treatments, providing them in a scalable format, and addressing transdiagnostic symptoms. This pilot trial examined the feasibility, acceptance, and preliminary effectiveness of a culturally adapted digital sleep intervention for refugees. Sixty-six refugees participated, with 68.2% of them seeking psychological help for the first time. Only three participants did not show clinically significant insomnia severity, 93.9% reported past traumatic experiences. Participants were randomly assigned to the intervention group (IG) or the waitlist control group (CG). Insomnia severity, measured by the Insomnia Severity Index, and secondary outcomes (sleep quality, fear of sleep, fatigue, depression, wellbeing, mental health literacy) were assessed at baseline, 1 and 3 months after randomization. The self-help intervention included four modules on sleep hygiene, rumination, and information on mental health conditions associated with sleep disturbances. 66.7% of the IG completed all modules. Satisfaction with the intervention and its perceived cultural appropriateness were high. Linear multilevel analyses revealed a small, non-significant intervention effect on insomnia severity of Hedge's g = 0.28 at 3-months follow-up, comparing the IG to the CG [F _{2, 60} = 0.88, p = 0.421]. This non-confirmatory pilot trial suggests that low-threshold, viable access to mental healthcare can be offered to multiple burdened refugees by culturally adapting an intervention, providing it in a scalable format, and addressing a transdiagnostic symptom.

ENIGMA-Sleep: Challenges, opportunities, and the road map

Neuroimaging and genetics studies have advanced our understanding of the neurobiology of sleep and its disorders. However, individual studies usually have limitations to identifying consistent and reproducible effects, including modest sample sizes, heterogeneous clinical characteristics and varied methodologies. These issues call for a large-scale multi-centre effort in sleep research, in order to increase the number of samples, and harmonize the methods of data collection, preprocessing and analysis using pre-registered well-established protocols. The Enhancing NeuroImaging Genetics through Meta-Analysis (ENIGMA) consortium provides a powerful collaborative framework for combining datasets across individual sites. Recently, we have launched the ENIGMA-Sleep working group with the collaboration of several institutes from 15 countries to perform large-scale worldwide neuroimaging and genetics studies for better understanding the neurobiology of impaired sleep quality in population-based healthy individuals, the neural consequences of sleep deprivation, pathophysiology of sleep disorders, as well as neural correlates of sleep disturbances across various neuropsychiatric disorders. In this introductory review, we describe the details of our currently available datasets and our ongoing projects in the ENIGMA-Sleep group, and discuss both the potential challenges and opportunities of a collaborative initiative in sleep medicine.

Subtypen der Insomnie – exemplarische Ansätze und offene Fragen

Verschiedene Autorinnen und Autoren nehmen an, dass es klinisch nützlich und wissenschaftlich erkenntnisbringend sein könnte, Subtypen der Insomnie zu identifizieren, um diese spezifisch und damit möglicherweise effektiver zu behandeln, als dies derzeit geschieht. Im vorliegenden Beitrag werden folgende exemplarisch ausgewählte Ansätze zur Einteilung der Insomnie in Subtypen vorgestellt: 1) Einteilungen nach klinischen Symptomen; 2) Primäre vs. sekundäre Insomnie; 3) Subtypen nach ICSD‑2; 4) Insomnie mit und ohne objektiv messbare kurze Schlafdauer; 5) Subtypen aus der Netherlands Sleep Registry. Anschließend werden die Stabilität der Zuordnung von einzelnen Patienten zu den verschiedenen Subtypen sowie die klinische Relevanz der Einteilungen kritisch diskutiert.

Effectiveness of an internet-based intervention to improve sleep difficulties in a culturally diverse sample of international students: A randomised controlled pilot study

Sleep difficulties are widespread among international students. Internet-based interventions are suggested as a low-threshold treatment option but may require cultural adaptation among culturally diverse populations. The present pilot study investigated the effectiveness and acceptance of an internet-based intervention to improve sleep difficulties in international students. A total of 81 international students of 36 nationalities were randomly assigned to the intervention (n = 41) or waitlist control group (n = 40). The intervention group received immediate access to a culturally non-adapted unguided internet-based sleep intervention consisting of three modules based on sleep hygiene and cognitive techniques to reduce rumination. At baseline, 4 and 12 weeks after randomisation, insomnia severity, measured by the Insomnia Severity Index, and secondary outcomes (sleep quality, depression, anxiety, perceived stress, well-being, presenteeism, mental health literacy) were assessed. Data were analysed using linear multi-level analyses. Additionally, satisfaction and perceived cultural appropriateness of the intervention were evaluated by international students after 4 weeks, and compared with ratings of German students, who represent the original target group. Insomnia severity improved over time in the intervention group compared to the control group, revealing a significant estimated mean difference of -5.60 (Hedges' g = 0.84, p < 0.001) after 12 weeks. Satisfaction and perceived cultural appropriateness was high and comparable to that of German students. The present study shows that a culturally non-adapted internet-based sleep intervention can be a low-threshold treatment option to help meet the high demand for mental healthcare among international students. It thus indicates that cultural adaptation might not represent a precondition for providing effective internet-based sleep interventions to this target group.

Co-ordination of brain and heart oscillations during non-rapid eye movement sleep

Oscillatory activities of the brain and heart show a strong variation across wakefulness and sleep. Separate lines of research indicate that non‐rapid eye movement (NREM) sleep is characterised by electroencephalographic slow oscillations (SO), sleep spindles, and phase–amplitude coupling of these oscillations (SO–spindle coupling), as well as an increase in high‐frequency heart rate variability (HF‐HRV), reflecting enhanced parasympathetic activity. The present study aimed to investigate further the potential coordination between brain and heart oscillations during NREM sleep. Data were derived from one sleep laboratory night with polysomnographic monitoring in 45 healthy participants (22 male, 23 female; mean age 37 years). The associations between the strength (modulation index [MI]) and phase direction of SO–spindle coupling (circular measure) and HF‐HRV during NREM sleep were investigated using linear modelling. First, a significant SO–spindle coupling (MI) was observed for all participants during NREM sleep, with spindle peaks preferentially occurring during the SO upstate (phase direction). Second, linear model analyses of NREM sleep showed a significant relationship between the MI and HF‐HRV (F = 20.1, r² = 0.30, p < 0.001) and a tentative circular‐linear correlation between phase direction and HF‐HRV (F = 3.07, r² = 0.12, p = 0.056). We demonstrated a co‐ordination between SO–spindle phase–amplitude coupling and HF‐HRV during NREM sleep, presumably related to parallel central nervous and peripheral vegetative arousal systems regulation. Further investigating the fine‐graded co‐ordination of brain and heart oscillations might improve our understanding of the links between sleep and cardiovascular health.

Guided Internet-Based Cognitive Behavioral Therapy for Insomnia: Health-Economic Evaluation From the Societal and Public Health Care Perspective Alongside a Randomized Controlled Trial

Background

The evidence base for internet-based cognitive behavioral therapy for insomnia (iCBT-I) is firm; however, little is known about iCBT-I’s health-economic effects.

Objective

This study aimed to evaluate the cost-effectiveness and cost–utility of iCBT-I in reducing insomnia among schoolteachers.

Methods

Schoolteachers (N=128) with clinically significant insomnia symptoms and work-related rumination were randomized to guided iCBT-I or a wait list control group, both with unrestricted access to treatment as usual. Health care use, patient and family expenditures, and productivity losses were self-assessed and used for costing from a societal and a public health care perspective. Costs were related to symptom-free status (score <8 on the insomnia severity index) and quality-adjusted life years (QALYs) gained. Sampling error was handled using nonparametric bootstrapping.

Results

Statistically significant differences favoring the intervention group were found for both health outcomes (symptom-free status yes or no: β=.30; 95% CI 0.16-0.43; QALYs: β=.019, 95% CI 0.01-0.03). From a societal perspective, iCBT-I had a 94% probability of dominating the wait list control for both health outcomes. From a public health care perspective, iCBT-I was more effective but also more expensive than the wait list control, resulting in an incremental cost-effectiveness ratio of €650 per symptom-free individual. In terms of QALYs, the incremental cost-effectiveness ratio was €11,285. At a willingness-to-pay threshold of €20,000 per QALY gained, the intervention’s probability of being cost-effective was 89%.

Conclusions

Our trial indicates that iCBT could be considered as a good value-for-money intervention for insomnia.

Trial Registration

German Clinical Trial Registry: DRKS00004700; https://tinyurl.com/2nnk57jm

International Registered Report Identifier (IRRID)

RR2-10.1186/1745-6215-14-169

Schlafmedizinische Qualifizierung in Deutschland – eine Bestandsaufnahme

Einleitung

Einblicke in die schlafmedizinische Versorgungsroutine sind nicht ohne Weiteres zu erhalten, wären für eine strategische Steuerung und prospektive Versorgungsplanung jedoch hilfreich. Ziel der vorliegenden Publikation ist die Bestandsaufnahme der aktuellen schlafmedizinischen Qualifizierungsmaßnahmen in Deutschland mit Schwerpunkt auf die Bereiche schlafbezogene Atmungsstörungen und Insomnie.

Materialien und Methoden

Die Analyse basiert u. a. auf der Gesundheitsberichterstattung des Bundes, den von den Landesärztekammern und Kassenärztlichen Vereinigungen bereitgestellten Daten, dem Mitgliederverzeichnis der Deutschen Gesellschaft für Schlafforschung und Schlafmedizin (DGSM) und den Daten der Kommission Zertifizierung und Qualitätssicherung der DGSM.

Ergebnisse

Die Gesundheitsberichterstattung des Bundes weist für 2018 insgesamt 1255 Schlafmedizinerinnen (im Folgenden wird zur besseren Lesbarkeit nur die weibliche Form genannt) in Deutschland aus. Nach den Daten der Landesärztekammern hingegen gab es 2020 insgesamt 1436 Schlafmedizinerinnen. Demnach verfügen nur etwa 0,4 % aller berufstätigen Ärztinnen über eine Zusatzbezeichnung Schlafmedizin. Die Mehrzahl sind Fachärztinnen für Innere Medizin (66,6 %), gefolgt von HNO-Heilkunde (12,5 %) und Neurologie (10,7 %). Deutlich höher ist die Anzahl der Ärztinnen mit Ermächtigung bzw. Zulassung zur Polygrafie. Laut DGSM gibt es in Deutschland derzeit 700 ärztliche Somnologinnen. Dies entspricht 0,17 % aller berufstätigen Ärztinnen. Die zertifizierten Schlaflabore werden zu etwa 70 % durch Pneumologinnen geleitet. Bislang haben 75 Personen einen freiwilligen Qualifikationsnachweis zur kognitiven Verhaltenstherapie bei Insomnie der DGSM erworben.

Schlussfolgerung

Die vorgelegten Daten machen deutlich, dass nur vergleichsweise wenige Fachärztinnen den Weg hin zu einer schlafmedizinischen Weiterbildung bzw. Qualifizierung wählen. Dies steht im erheblichen Kontrast zur weiten Verbreitung insbesondere der schlafbezogenen Atmungsstörungen und der Insomnien, die klassische Volkskrankheiten darstellen.

Auditorische Stimulation während des Schlafs

Die Insomnie, d. h. eine Ein- und/oder Durchschlafstörung, die sich negativ auf die Leistungsfähigkeit und Tagesbefindlichkeit auswirkt, ist eine der häufigsten Erkrankungen in der Allgemeinbevölkerung. Sie wird derzeit meistens pharmakologisch und/oder psychotherapeutisch behandelt, wobei die pharmakologische Behandlung mit Benzodiazepin-Rezeptor-Agonisten zu Abhängigkeit führen kann und die Verfügbarkeit von für die Insomnie-Therapie ausgebildeten Psychotherapeuten momentan nicht in ausreichendem Maße gegeben ist. Durch innovative Behandlungsmethoden könnte hier eine Versorgungslücke effektiv geschlossen werden. Hierzu zählt die auditorische Stimulation, welche vorhandene Sinneskanäle nutzt, um den Schlaf zu beeinflussen. Bisher wurde die auditorische Stimulation vor allem zur Untersuchung von Prozessen der Gedächtniskonsolidierung bei gesunden Probanden angewendet, wobei erfolgreich eine Erhöhung langsamer Oszillationen erreicht wurde, welche vor allem während des Tiefschlafs auftreten. Erste Befunde und sekundäre Outcome-Parameter liefern Hinweise, dass die Potenzierung langsamer Oszillationen durch auditorische Stimulation den Schlaf vertiefen kann, jedoch wurde hierzu bislang keine Studie mit Insomniepatienten durchgeführt. Weitere Forschung bezüglich des Einflusses der Potenzierung langsamer Oszillationen auf die Linderung von Ein- und Durchschlafproblemen bei vorliegender nichtorganischer Insomnie erscheint daher geboten zu sein, um der hohen Beschwerdelast dieser Patientengruppe entgegenzuwirken.

Psychological interventions to improve sleep in college students: A meta-analysis of randomized controlled trials

Sleep disturbances and insomnia are common in college students, and reduce their quality of life and academic performance. The aim of this meta-analysis was to evaluate the efficacy of psychological interventions aimed at improving sleep in college students. A meta-analysis was conducted with 10 randomized controlled trials with passive control conditions (N = 2,408). The overall mean effect size (Hedges' g) of all sleep-related outcomes within each trial was moderate to large (g = 0.61; 95% confidence interval: 0.41-0.81; numbers-needed-to-treat = 3). Effect sizes for global measures of sleep disturbances were g = 0.79; 95% confidence interval: 0.52-1.06; and for sleep-onset latency g = 0.65; 95% confidence interval: 0.36-0.94. The follow-up analyses revealed an effect size of g = 0.56; 95% confidence interval: 0.45-0.66 for the combined sleep-related outcomes based on three studies. No significant covariates were identified. These results should be interpreted cautiously due to an overall substantial risk of bias, and in particular with regard to blinding of participants and personnel. Nevertheless, they provide evidence that psychological interventions for improving sleep are efficacious among college students. Further research should explore long-term effects and potential moderators of treatment efficacy in college students.

Affect and Arousal in Insomnia: Through a Lens of Neuroimaging Studies

PURPOSE OF REVIEW

Previous research has struggled with identifying clear-cut, objective counterparts to subjective distress in insomnia. Approaching this discrepancy with a focus on hyperarousal and dysfunctional affective processes, studies examining brain structures and neural networks involved in affect and arousal are reviewed and conclusions for an updated understanding of insomnia are drawn.

RECENT FINDINGS

Recent studies found that amygdala reactivity, morphometry and adaptation in insomnia are altered, indicating that processing of negative stimuli is intensified and more lasting. Also, patients with insomnia show aberrant connectivity in the default mode network (DMN) and the salience network (SN), which is associated with subjective sleep disturbances, hyperarousal, maladaptive emotion regulation and disturbed integration of emotional states. The limbic circuit is assumed to play a crucial role in enhanced recall of negative experiences. There is reason to consider insomnia as a disorder of affect and arousal. Dysregulation of the limbic circuit might perpetuate impaired connectivity in the DMN and the SN. However, the interplay between the networks is yet to be researched.

Cognitive behavioural therapy for insomnia does not appear to have a substantial impact on early markers of cardiovascular disease: A preliminary randomized controlled trial

According to the World Health Organization, cardiovascular diseases are the leading cause of death in the world. Therefore, early prevention of these diseases is a public health priority. Epidemiological data suggest that insomnia may be a modifiable risk factor for cardiovascular diseases. A randomized controlled trial in a sample of insomnia patients without cardiovascular disease was conducted to investigate the effects of insomnia treatment on early markers of cardiovascular diseases assessed by 24-hr ambulatory blood pressure, heart rate and heart rate variability monitoring, and morning fasting blood samples. Forty-six patients with insomnia disorder were randomized to cognitive behavioural therapy for insomnia (CBT-I; n = 23) or a waitlist control condition (n = 23). Contrary to the hypothesis, intention-to-treat analyses did not show any significant treatment effects on early markers of cardiovascular disease (d = 0.0-0.6) despite successful insomnia treatment (d = 1.3). Potential methodological and conceptual reasons for these negative findings are discussed. Future studies might include larger sample sizes that are at risk of cardiovascular diseases and focus on other cardiovascular markers.

A Systematic Review and Network Meta-Analysis of Randomized Controlled Trials Evaluating the Evidence Base of Melatonin, Light Exposure, Exercise, and Complementary and Alternative Medicine for Patients with Insomnia Disorder

Insomnia is a prevalent disorder and it leads to relevant impairment in health-related quality of life. Recent clinical guidelines pointed out that Cognitive-Behavior Therapy for Insomnia (CBT-I) should be considered as first-line intervention. Nevertheless, many other interventions are commonly used by patients or have been proposed as effective for insomnia. These include melatonin, light exposure, exercise, and complementary and alternative medicine. Evaluation of comparable effectiveness of these interventions with first-line intervention for insomnia is however still lacking. We conducted a systematic review and network meta-analysis on the effects of these interventions. PubMed, PsycInfo, PsycArticles, MEDLINE, and CINAHL were systematically searched and 40 studies were included in the systematic review, while 36 were entered into the meta-analysis. Eight network meta-analyses were conducted. Findings support effectiveness of melatonin in improving sleep-onset difficulties and of meditative movement therapies for self-report sleep efficiency and severity of the insomnia disorder. Some support was observed for exercise, hypnotherapy, and transcranial magnetic resonance, but the number of studies for these interventions is still too small. None of the considered interventions received superior evidence to CBT-I, which should be more widely disseminated in primary care.

Hippocampal and medial prefrontal cortical volume is associated with overnight declarative memory consolidation independent of specific sleep oscillations

The current study was designed to further clarify the influence of brain morphology, sleep oscillatory activity and age on memory consolidation. Specifically, we hypothesized, that a smaller volume of hippocampus, parahippocampal and medial prefrontal cortex negatively impacts declarative, but not procedural, memory consolidation. Explorative analyses were conducted to demonstrate whether a decrease in slow-wave activity negatively impacts declarative memory consolidation, and whether these factors mediate age effects on memory consolidation. Thirty-eight healthy participants underwent an acquisition session in the evening and a retrieval session in the morning after night-time sleep with polysomnographic monitoring. Declarative memory was assessed with the paired-associate word list task, while procedural memory was tested using the mirror-tracing task. All participants underwent high-resolution magnetic resonance imaging. Participants with smaller hippocampal, parahippocampal and medial prefrontal cortex volumes displayed a reduced overnight declarative, but not procedural memory consolidation. Mediation analyses showed significant age effects on overnight declarative memory consolidation, but no significant mediation effects of brain morphology on this association. Further mediation analyses showed that the effects of age and brain morphology on overnight declarative memory consolidation were not mediated by polysomnographic variables or sleep electroencephalogram spectral power variables. Thus, the results suggest that the association between age, specific brain area volume and overnight memory consolidation is highly relevant, but does not necessarily depend on slow-wave sleep as previously conceptualized.

The effects of digital cognitive behavioral therapy for insomnia on cognitive function: a randomized controlled trial

Study Objectives

We sought to examine the impact of digital cognitive behavioral therapy (dCBT) for insomnia on both self-reported cognitive impairment and objective cognitive performance.

Methods

The Defining the Impact of Sleep improvement on Cognitive Outcomes (DISCO) trial was an online, two-arm, single-blind, randomized clinical trial of dCBT versus wait-list control. Participants were aged 25 years and older, met DSM-5 diagnostic criteria for insomnia disorder, and reported difficulties with concentration or memory. Assessments were carried out online at baseline, and 10 and 24 weeks post-randomization. The primary outcome measure was self-reported cognitive impairment, assessed with the British Columbia Cognitive Complaints Inventory (BC-CCI). Secondary outcomes included tests of cognitive performance, insomnia symptoms, cognitive failures, fatigue, sleepiness, depression, and anxiety.

Results

Four hundred and ten participants with insomnia were recruited and assigned to dCBT (N = 205) or wait-list control (N = 205). At 10 weeks post-randomization the estimated adjusted mean difference for the BC-CCI was −3.03 (95% CI: −3.60, −2.47; p &lt; 0.0001, d = −0.86), indicating that participants in the dCBT group reported less cognitive impairment than the control group. These effects were maintained at 24 weeks (d = −0.96) and were mediated, in part, via reductions in insomnia severity and increased sleep efficiency. Treatment effects in favor of dCBT, at both 10 and 24 weeks, were found for insomnia severity, sleep efficiency, cognitive failures, fatigue, sleepiness, depression, and anxiety. We found no between-group differences in objective tests of cognitive performance.

Conclusions

Our study shows that dCBT robustly decreases self-reported cognitive impairment at post-treatment and these effects are maintained at 6 months.