Exploring the Multidimensional Assessment of Interoceptive Awareness in youth aged 7-17 years.

OBJECTIVE: This study aimed to adapt the Multidimensional Assessment of Interoceptive Awareness (MAIA) questionnaire for younger respondents. METHOD: The language of the MAIA was revised and children aged 7-10 years (n = 212) and adolescents aged 11-17 years (n = 217) completed the questionnaire. RESULTS: The original eight-factor model was tested for fit using confirmatory factor analysis. The model had an acceptable fit in the total sample and younger subsample and overall fit in the older subsample was adequate following modification. Internal consistency was good, except for the Noticing, Not-Distracting and Not-Worrying scales. Results also demonstrated a negative linear relationship between the trusting scale and age, suggesting that youths may lose trust in their body as they age. CONCLUSION: The adapted MAIA can be used with a younger population and, depending on the research question, individual MAIA scales may be selected. The survey is available at https://osher.ucsf.edu/maia.

DNA Methylation Changes in the Sperm of Captive-Reared Fish: A Route to Epigenetic Introgression in Wild Populations.

Interbreeding between hatchery-reared and wild fish, through deliberate stocking or escapes from fish farms, can result in rapid phenotypic and gene expression changes in hybrids, but the underlying mechanisms are unknown. We assessed if one generation of captive breeding was sufficient to generate inter- and/or transgenerational epigenetic modifications in Atlantic salmon. We found that the sperm of wild and captive-reared males differed in methylated regions consistent with early epigenetic signatures of domestication. Some of the epigenetic marks that differed between hatchery and wild males affected genes related to transcription, neural development, olfaction, and aggression, and were maintained in the offspring beyond developmental reprogramming. Our findings suggest that rearing in captivity may trigger epigenetic modifications in the sperm of hatchery fish that could explain the rapid phenotypic and genetic changes observed among hybrid fish. Epigenetic introgression via fish sperm represents a previously unappreciated mechanism that could compromise locally adapted fish populations.

The relationship between self-harm and alexithymia: A systematic review and meta-analysis.

Self-harm, defined for the purpose of this review as any act of self-injury without explicit suicidal intent, is an increasing public health concern, with potential long-term implications for those who engage in it. Previous research has identified a correlational relationship between self-harm and alexithymia, an emotion processing deficit characterized by difficulties identifying and describing feelings, and an externally orientated thinking style. Through a systematic search of the literature, the current review examines the association between alexithymia and self-harm. A meta-analysis based on 23 studies found a significant, positive relationship between self-harm and alexithymia, with a medium effect size (g = 0.57, 95% CI 0.46-0.69). All 23 studies used the Toronto Alexithymia Scale (TAS20) to measure alexithymia. The alexithymia subcomponents difficulty identifying feelings and difficulty describing feelings were significantly associated with self-harm, but there was no significant association between self-harm and externally orientated thinking. The effect size of the relationship was significantly larger in adolescent samples compared with adult samples and in female compared with male samples. The definition of self-harm did not affect the effect size of the relationship between alexithymia and self-harm and the results are consistent with previous meta-analyses focused more narrowly on non-suicidal self-injury and, separately, suicidal behaviors. Heterogeneity between the included studies was high. The results support an affect regulation model of self-harm, in which self-harm is used to regulate an emotional experience that is poorly understood.

Tests of pattern separation and pattern completion in humans-A systematic review.

To systematically review the characteristics, validity and outcome measures of tasks that have been described in the literature as assessing pattern separation and pattern completion in humans. Electronic databases were searched for articles. Parameters for task validity were obtained from two reviews that described optimal task design factors to evaluate pattern separation and pattern completion processes. These were that pattern separation should be tested during an encoding task using abstract, never-before-seen visual stimuli, and pattern completion during a retrieval task using partial cues; parametric alteration of the degree of interference of stimuli or degradation of cues should be used to generate a corresponding gradient in behavioral output; studies should explicitly identify the specific memory domain under investigation (sensory/perceptual, temporal, spatial, affect, response, or language) and account for the contribution of other potential attributes involved in performance of the task. A systematic, qualitative assessment of validity in relation to these parameters was performed, along with a review of general validity and task outcome measures. Sixty-two studies were included. The majority of studies investigated pattern separation and most tasks were performed on young, healthy adults. Pattern separation and pattern completion were most frequently tested during a retrieval task using familiar or recognizable visual stimuli and cues. Not all studies parametrically altered the degree of stimulus interference or cue degradation, or controlled for potential confounding factors. This review found evidence that some of the parameters for task validity have been followed in some human studies of pattern separation and pattern completion, but no study was judged to have adequately met all the parameters for task validity. The contribution of these parameters and other task design factors towards an optimal behavioral paradigm is discussed and recommendations for future research are made. © 2015 Wiley Periodicals, Inc.

Psychometric properties of multicomponent tools designed to assess frailty in older adults: A systematic review.

BACKGROUND: Frailty is widely recognised as a distinct multifactorial clinical syndrome that implies vulnerability. The links between frailty and adverse outcomes such as death and institutionalisation have been widely evidenced. There is currently no gold standard frailty assessment tool; optimizing the assessment of frailty in older people therefore remains a research priority. The objective of this systematic review is to identify existing multi-component frailty assessment tools that were specifically developed to assess frailty in adults aged ≥60 years old and to systematically and critically evaluate the reliability and validity of these tools. METHODS: A systematic literature review was conducted using the standardised COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) checklist to assess the methodological quality of included studies. RESULTS: Five thousand sixty-three studies were identified in total: 73 of which were included for review. 38 multi-component frailty assessment tools were identified: Reliability and validity data were available for 21 % (8/38) of tools. Only 5 % (2/38) of the frailty assessment tools had evidence of reliability and validity that was within statistically significant parameters and of fair-excellent methodological quality (the Frailty Index-Comprehensive Geriatric Assessment [FI-CGA] and the Tilburg Frailty Indicator [TFI]). CONCLUSIONS: The TFI has the most robust evidence of reliability and validity and has been the most extensively examined in terms of psychometric properties. However, there is insufficient evidence at present to determine the best tool for use in research and clinical practice. Further in-depth evaluation of the psychometric properties of these tools is required before they can fulfil the criteria for a gold standard assessment tool.

Interventions for reducing benzodiazepine use in older people: meta-analysis of randomised controlled trials.

BACKGROUND: The use of benzodiazepines has been advised against in older people, but prevalence rates remain high. AIMS: To review the evidence for interventions aimed at reducing benzodiazepine use in older people. METHOD: We conducted a systematic review, assessment of risk of bias and meta-analyses of randomised controlled trials of benzodiazepine withdrawal and prescribing interventions. RESULTS: Ten withdrawal and eight prescribing studies met the inclusion criteria. At post-intervention, significantly higher odds of not using benzodiazepines were found with supervised withdrawal with psychotherapy (odds ratio (OR) = 5.06, 95% CI 2.68-9.57, P<0.00001) and withdrawal with prescribing interventions (OR = 1.43, 95% CI 1.02-2.02, P = 0.04) in comparison with the control interventions treatment as usual (TAU), education placebo, withdrawal with or without drug placebo, or psychotherapy alone. Significantly higher odds of not using benzodiazepines were also found for multifaceted prescribing interventions (OR = 1.37, 95% CI 1.10-1.72, P = 0.006) in comparison with control interventions (TAU and prescribing placebo). CONCLUSIONS: Supervised benzodiazepine withdrawal augmented with psychotherapy should be considered in older people, although pragmatic reasons may necessitate consideration of other strategies such as medication review.

Maximising signal-to-noise ratios in environmental DNA-based monitoring.

Man's impacts on global ecosystems are increasing and there is a growing demand that these activities be appropriately monitored. Monitoring requires measurement of a response metric ('signal') that changes maximally and consistently in response to the monitored activity irrespective of other factors ('noise'), thus maximising the signal-to-noise ratio. Indices derived from time-consuming morphology-based taxonomic identification of organisms are a core part of many monitoring programmes. Metabarcoding is an alternative to morphology-based identification and involves the sequencing of short fragments of DNA ('markers') from multiple taxa simultaneously. DNA suitable for metabarcoding includes that extracted from environmental samples (eDNA). Metabarcoding outputs DNA sequences that can be identified (annotated) by matching them against archived annotated sequences. However, sequences from most organisms are not archived - preventing annotation and potentially limiting metabarcoding in monitoring applications. Consequently, there is growing interest in using unannotated sequences as response metrics in monitoring programmes. We compared the sequences from three commonly used markers (16S (V3/V4 regions), 18S (V1/V2 regions) and COI) and, sampling along steep impact gradients, showed that the 16S and COI sequences were associated with the largest and smallest signal-to-noise ratio respectively. We trialled four separate, intuitive, noise-reduction approaches and demonstrated that removing less frequent sequences improved the signal-to-noise ratio, partitioning an additional 25 % from noise to explanatory factors in non-parametric ANOVA (NPA) and reducing dispersion in the data. For the 16S marker, retaining only the most frequently observed sequence, per sample, resulting in nine sequences across 150 samples, generated a near-maximal signal-to-noise ratio (95 % of the variance explained in NPA). We recommend that NPA, combined with rigorous elimination of less frequent sequences, be used to pre-filter sequences/taxa being used in monitoring applications. Our approach will simplify downstream analysis, for example the identification of key taxa and functional associations.

Impact of the covid-19 pandemic on amyotrophic lateral sclerosis care in the UK.

The Covid-19 pandemic has impacted healthcare. Our aim was to identify how amyotrophic lateral sclerosis (ALS) care in the UK has been affected by the pandemic by exploring the experiences of people living with ALS (plwALS), healthcare professionals (HCPs) working with plwALS, and ALS care centers. Three surveys were carried out to explore the experiences of plwALS, HCPs and ALS care centers during the pandemic. Quantitative data were analyzed using descriptive and inferential statistics and triangulated with the qualitative data which were analyzed thematically. Responses from 53 plwALS, 73 HCPs and 23 ALS care centers were analyzed. Five main themes were identified: keeping safe, losses, negative emotions, delivering care and alternative care delivery in a pandemic. PlwALS and HCPs felt that care was sub-optimal as a result of the pandemic. Changes to care included longer waiting times and face-to-face appointments being canceled or replaced by virtual consultations. While benefits of virtual consultations were reported, concerns were raised about incomplete clinical assessments and the disruption of provision of testing and interventions. ALS care has changed as a result of the pandemic. Patients have had a lack of face-to-face contact with HCPs and have experienced delays to investigations and treatments. PlwALS and HCPs were concerned about the impact of this change, but the long-term implications remain unclear. We propose recommendations for HCPs caring for plwALS, that will promote continuity of evidenced based care in the context of a pandemic.

"My Heart and My Brain Is What's Bleeding, These Are Just Cuts." An Interpretative Phenomenological Analysis of Young Women's Experiences of Self-Harm.

Engagement in self-harm, defined as intentional self-poisoning or self-injury irrespective of the apparent purpose of the act, is increasing, particularly among girls and young women. Understanding the behavior from the perspective of those who self-harm is, therefore, vital in designing effective interventions and treatments. The current brief research report presents a key theme from an Interpretative Phenomenological Analysis of the experience of self-harm among eight young women, aged between 18 and 29. The theme Is Self-Harm Bad? concerns the way in which participants both acknowledged and resisted a negative conception of self-harm that was often constructed from other people's attitudes. Three subthemes explore the reasons why participants were reluctant to endorse self-harm as bad: Self-Harm is the Symptom, Self-Harm Works (Until it Doesn't) and Self-Harm is Part of Me. The findings highlight the disparity between the characterization of self-harm as a highly risky behavior and the lived experience of self-harm as a functional means of emotion regulation. From a clinical perspective, the findings explored in this brief report suggest that highlighting the risks of self-harm may not be a sufficient deterrent. The recently revised draft National Institute for Health and Care Excellence (NICE) guidance recommends that everyone presenting to hospital following self-harm should be given a comprehensive psychosocial assessment, of which the function is, in part, to understand why the person has self-harmed. The current study underlines the importance of seeing past the behavior to the underlying causes and exploring the meaning of self-harm to the individual in order to implement effective preventative interventions.

Attentional biases using the body in the crowd task: are angry body postures detected more rapidly?

Research using schematic faces has consistently demonstrated attentional biases towards threatening information (angry faces), which are accentuated for individuals with higher levels of anxiety. However, research has yet to reveal whether this is the case for other nonverbal channels of communication. In the research reported here, ninety-five undergraduates completed a body in the crowd task analogous to the face in the crowd task, to examine whether attentional biases for threat existed for schematic body postures. Participants demonstrated faster detection of threat. A discrepant angry posture in a neutral crowd was identified quicker than a discrepant happy posture in a neutral crowd. This effect was pronounced for individuals with higher self-reported levels of trait anxiety. Results also demonstrated evidence of delayed disengagement from threat. Individuals were slower (i.e., more distracted) by identical crowds of angry postures rather than happy or neutral crowds and were slower to detect a discrepant neutral posture among an angry crowd than neutral among a happy crowd. These findings are the first to establish threat biases using body postures in a visual search paradigm. The results are in accordance with previous research using schematic face stimuli. Theoretical and practical implications are discussed.

Types of interference and their resolution in monolingual word production.

There is growing evidence that speakers recruit inhibitory control in situations of high within-language interference, e.g., when selecting from among competing lexical entries or when tailoring utterances to the communicative needs of the addressee. However, little is known about the types of cognitive control mechanisms that are involved in the speech production process. This study examines the relative contribution of various forms of interference arising at different stages of information processing as well as their control to object naming under conditions of prepotent and underdetermined competition. Eighty-nine unimpaired native English speakers completed three inhibitory control tasks (arrow flanker, Simon arrow and anti-saccade) and two object naming tasks (picture-word interference, PWI, and name agreement, NA). Analyses of mean RT and RT distribution (delta plots) showed that only the flanker effect was a significant predictor of the PWI but not NA effect, while the remaining inhibitory measures made no significant contribution to either the PWI or NA effect. Participants with smaller flanker effects, indicative of better resolution of representational conflict, were faster to name objects in the face of competing stimuli. The pattern of results suggests that delays in production can be an outcome of inefficient resolution of interference traced to intermediate rather than late stages of processing, at least as far as the PWI task is concerned.

Near neutrality, rate heterogeneity, and linkage govern mitochondrial genome evolution in Atlantic cod (Gadus morhua) and other gadine fish.

The mitochondrial DNA (mtDNA) genome figures prominently in evolutionary investigations of vertebrate animals due to a suite of characteristics that include absence of Darwinian selection, high mutation rate, and inheritance as a single linkage group. Given complete linkage and selective neutrality, mtDNA gene trees are expected to correspond to intraspecific phylogenies, and mtDNA diversity will reflect population size. The validity of these assumptions is, however, rarely tested on a genome-wide scale. Here, we analyze rates and patterns of molecular evolution among 32 whole mitochondrial genomes of Atlantic Cod (Gadus morhua) as compared with its sister taxon, the walleye pollock (Gadus [Theragra] chalcogrammus), and genomes of seven other gadine codfish. We evaluate selection within G. morhua, between sister species, and among species and intraspecific measures of linkage disequilibrium and recombination within G. morhua. Strong rate heterogeneity occurs among sites and genes at all levels of hierarchical comparison, consistent with variation in mutation rates across the genome. Neutrality indices (dN/dS) are significantly greater than unity among G. morhua genomes and between sister species, which suggests that polymorphisms within species are slightly deleterious, as expected under the nearly neutral theory of molecular evolution. Among species of gadines, dN/dS ratios are heterogeneous among genes, consistent with purifying selection and variation in functional constraint among genes rather than positive selection. The dN/dS ratio for ND4L is anomalously high across all hierarchical levels. There is no evidence for recombination within G. morhua. These patterns contrast strongly with those reported for humans: genome-wide patterns in other vertebrates should be investigated to elucidate the complex patterns of mtDNA molecular evolution.

An online mindfulness intervention to enhance compassion in nursing practice: A feasibility and acceptability study with nursing students.

Background: Compassion is an important component of nursing care, but public enquiries into care failures have noted that it is not always evident. Mindfulness interventions have the potential to support compassion. However, the feasibility of delivering a mindfulness intervention at scale to nursing students has not been established. Objectives: To develop and test the feasibility and acceptability of a tailored mindfulness based online intervention to foster compassion in nursing students within clinical practice. Design: A randomised feasibility study with a waiting list control. Setting: A UK nursing faculty within a large university. Participants: Post-graduate, post-registration and pre-registration nursing students (N = 77). Methods: An online five module mindfulness based intervention (Mindful Nursing Online) was developed and tailored to support compassion in clinical nursing. The feasibility study comprised 77 participants randomised in a 2:1 ratio into an immediate access group (intervention, n = 50) or a delayed access group (waiting list control, n = 27). Data on feasibility through completion, attrition and practice rates, were collected through follow-up questionnaires at post-intervention, and 14 and 20 weeks after baseline. Acceptability data was collected through semi-structured interviews with 12 participants. Results: Non-completion rates were high with all five modules completed by only 28% (n = 14) of participants, and three modules completed by only 46% (n = 23). The most commonly cited reason for non-completion was lack of time. However, the interview data suggested those who completed the intervention were using mindfulness techniques in practice. They described feeling less stressed on the ward, having an increased focus on patients and a greater appreciation of the importance of self-care. Evaluative feedback therefore showed that the intervention was perceived to be effective at promoting mindfulness skills and was relevant to nursing work. Conclusion: Minimising attrition and enhancing engagement with the intervention should be the key objectives of a future study. Feedback from participants who completed the intervention indicates that a brief mindfulness intervention delivered online may support the delivery of compassionate nursing care.

Effects of mindfulness-based interventions on alexithymia: a systematic review.

QUESTION: Alexithymia has been found to be modifiable through treatment, with associated clinical benefits. Recent studies have begun to test the potential of mindfulness-based interventions to reduce alexithymia, using skills-based, group training to improve non-judgemental, present-moment awareness. The objective of this review therefore was to conduct a systematic synthesis to assess the current state of knowledge about the effect of mindfulness-based interventions on alexithymia to inform clinical practice. STUDY SELECTION AND ANALYSIS: We carried out a systematic review of the literature and found four randomised controlled trials of the effect of mindfulness-based interventions on alexithymia, with a combined total of 460 participants. FINDINGS: A random-effects meta-analysis, combining study endpoint data, showed a statistically significant effect of mindfulness-based treatment on alexithymia (Toronto Alexithymia Scale) compared with the control group (mean difference=-5.28, 95% CI -9.28 to -1.28, p=0.010). Subgroup analysis was conducted to investigate sources of heterogeneity (I2=52%). Heterogeneity was reduced when the meta-analysis was restricted to interventions of a similar duration (3 months or less). CONCLUSIONS: Findings from our study should be replicated in further research with larger samples; however, the results indicate that mindfulness-based interventions may be an effective treatment in reducing alexithymia.

Multicomponent Frailty Assessment Tools for Older People with Psychiatric Disorders: A Systematic Review.

OBJECTIVE: To review evidence evaluating the use of multicomponent frailty assessment tools in assessing frailty in older adults with psychiatric disorders. METHODS: A systematic literature review was conducted to identify all multicomponent frailty assessment tools (ie, a tool that assesses two or more indicators of frailty). The items of each frailty assessment tool were compared with Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5) diagnostic criteria for psychiatric disorders to assess construct overlap. Studies conducted in community, inpatient, and outpatient clinical settings were considered for inclusion. PARTICIPANTS: Adults aged 60 years or older. RESULTS: A total of 5639 records were identified following the removal of duplicates, from which 95 studies were included for review. Of the 48 multicomponent frailty assessment tools identified, no tool had been developed for, or validated in, older adult populations with a psychiatric disorder. Overall, 20 of 48 frailty assessment tools contained a psychological assessment domain, with 17 of 48 tools citing the presence of depressed mood and/or anxiety as a frailty indicator. Common areas of construct overlap in frailty assessment tools and DSM-5 diagnostic criteria included weight loss (29 of 48) and fatigue (21 of 48). CONCLUSIONS: Significant construct overlap exists between the indicators of frailty as conceptualized in existing frailty assessment tools and DSM-5 diagnostic criteria for common psychiatric disorders including major depressive episode and generalized anxiety disorder that has the potential to confound frailty assessment results. Further research is necessary to establish a reliable and valid tool to assess frailty in this population. J Am Geriatr Soc 67:1085-1095, 2019.

Predictors of treatment outcome in depression in later life: A systematic review and meta-analysis.

BACKGROUND: Predictor analyses of late-life depression can be used to identify variables associated with outcomes of treatments, and hence ways of tailoring specific treatments to patients. The aim of this review was to systematically identify, review and meta-analyse predictors of outcomes of any type of treatment for late-life depression. METHODS: Pubmed, Embase, CINAHL, Web of Science and PsycINFO were searched for studies published up to December 2016. Primary and secondary studies reported treatment predictors from randomised controlled trials of any treatment for patients with major depressive disorder aged over 60 were included. Treatment outcomes included response, remission and change in depression score. RESULTS: Sixty-seven studies met the inclusion criteria. Of 65 identified statistically significant predictors, only 7 were reported in at least 3 studies. Of these, 5 were included in meta-analyses, and only 3 were statistically significant. Most studies were rated as being of moderate to strong quality and satisfied key quality criteria for predictor analyses. LIMITATIONS: The searches were limited to randomised controlled trials and most of the included studies were secondary analyses. CONCLUSIONS: Baseline depression severity, co-morbid anxiety, executive dysfunction, current episode duration, early improvement, physical illnesses and age were reported as statistically significant predictors of treatment outcomes. Only the first three were significant in meta-analyses. Subgroup analyses showed differences in predictor effect between biological and psychosocial treatment. However, high heterogeneity and small study numbers suggest a cautious interpretation of results. These predictors were associated with various mechanisms including brain pathophysiology, perceived social support and proposed distinct types of depressive disorder. Further investigation of the clinical utility of these predictors is suggested.

A weak scientific basis for gaming disorder: Let us err on the side of caution.

We greatly appreciate the care and thought that is evident in the 10 commentaries that discuss our debate paper, the majority of which argued in favor of a formalized ICD-11 gaming disorder. We agree that there are some people whose play of video games is related to life problems. We believe that understanding this population and the nature and severity of the problems they experience should be a focus area for future research. However, moving from research construct to formal disorder requires a much stronger evidence base than we currently have. The burden of evidence and the clinical utility should be extremely high, because there is a genuine risk of abuse of diagnoses. We provide suggestions about the level of evidence that might be required: transparent and preregistered studies, a better demarcation of the subject area that includes a rationale for focusing on gaming particularly versus a more general behavioral addictions concept, the exploration of non-addiction approaches, and the unbiased exploration of clinical approaches that treat potentially underlying issues, such as depressive mood or social anxiety first. We acknowledge there could be benefits to formalizing gaming disorder, many of which were highlighted by colleagues in their commentaries, but we think they do not yet outweigh the wider societal and public health risks involved. Given the gravity of diagnostic classification and its wider societal impact, we urge our colleagues at the WHO to err on the side of caution for now and postpone the formalization.

Scholars' open debate paper on the World Health Organization ICD-11 Gaming Disorder proposal.

Concerns about problematic gaming behaviors deserve our full attention. However, we claim that it is far from clear that these problems can or should be attributed to a new disorder. The empirical basis for a Gaming Disorder proposal, such as in the new ICD-11, suffers from fundamental issues. Our main concerns are the low quality of the research base, the fact that the current operationalization leans too heavily on substance use and gambling criteria, and the lack of consensus on symptomatology and assessment of problematic gaming. The act of formalizing this disorder, even as a proposal, has negative medical, scientific, public-health, societal, and human rights fallout that should be considered. Of particular concern are moral panics around the harm of video gaming. They might result in premature application of diagnosis in the medical community and the treatment of abundant false-positive cases, especially for children and adolescents. Second, research will be locked into a confirmatory approach, rather than an exploration of the boundaries of normal versus pathological. Third, the healthy majority of gamers will be affected negatively. We expect that the premature inclusion of Gaming Disorder as a diagnosis in ICD-11 will cause significant stigma to the millions of children who play video games as a part of a normal, healthy life. At this point, suggesting formal diagnoses and categories is premature: the ICD-11 proposal for Gaming Disorder should be removed to avoid a waste of public health resources as well as to avoid causing harm to healthy video gamers around the world.

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

BACKGROUND: Sleep difficulties might be a contributory causal factor in the occurrence of mental health problems. If this is true, improving sleep should benefit psychological health. We aimed to determine whether treating insomnia leads to a reduction in paranoia and hallucinations. METHODS: We did this single-blind, randomised controlled trial (OASIS) at 26 UK universities. University students with insomnia were randomly assigned (1:1) with simple randomisation to receive digital cognitive behavioural therapy (CBT) for insomnia or usual care, and the research team were masked to the treatment. Online assessments took place at weeks 0, 3, 10 (end of therapy), and 22. The primary outcome measures were for insomnia, paranoia, and hallucinatory experiences. We did intention-to-treat analyses. The trial is registered with the ISRCTN registry, number ISRCTN61272251. FINDINGS: Between March 5, 2015, and Feb 17, 2016, we randomly assigned 3755 participants to receive digital CBT for insomnia (n=1891) or usual practice (n=1864). Compared with usual practice, the sleep intervention at 10 weeks reduced insomnia (adjusted difference 4·78, 95% CI 4·29 to 5·26, Cohen's d=1·11; p<0·0001), paranoia (-2·22, -2·98 to -1·45, Cohen's d=0·19; p<0·0001), and hallucinations (-1·58, -1·98 to -1·18, Cohen's d=0·24; p<0·0001). Insomnia was a mediator of change in paranoia and hallucinations. No adverse events were reported. INTERPRETATION: To our knowledge, this is the largest randomised controlled trial of a psychological intervention for a mental health problem. It provides strong evidence that insomnia is a causal factor in the occurrence of psychotic experiences and other mental health problems. Whether the results generalise beyond a student population requires testing. The treatment of disrupted sleep might require a higher priority in mental health provision. FUNDING: Wellcome Trust.