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.
Bibliographical noteFunding Information:
The study was done by the University of Oxford Sleep and Circadian Neuroscience Institute, with a grant from the Wellcome Trust (098461/Z/12/Z). The sleep treatment programme was provided to all the trial participants at no cost by Sleepio/Big Health Ltd. RGF and GMG are the principal investigators for the grant, and DFr and PJH are grant holders. BS is directly funded by the grant. The research in Nottingham (CHo, EBD, CG) was supported by the National Institute of Health Research (NIHR) MindTech Healthcare Technology Co-operative. DFr is supported by an NIHR Research Professorship. This study was funded by the Wellcome Trust and supported by the NIHR Oxford Health Biomedical Research Centre. The views expressed are those of the authors and not necessarily those of the National Health Service, NIHR, or Department of Health.
DFr reports grants from Wellcome Trust, non-financial support (provision of the sleep treatment for the OASIS trial) from Sleepio, and grants from the UK National Institute of Health Research (NIHR), during the conduct of the study, and personal fees from Oxford Virtual Reality, a University of Oxford spin-out company, outside the submitted work. BS reports grants from Wellcome Trust, during the conduct of the study, and personal fees from Big Health Ltd, outside the submitted work. GMG reports personal fees from Servier, Lundbeck and Otsuka, Takeda, Merck, Medscape, Pfizer, P1vital, Compass Pathways, Shire, Angelini Spa, and Allergan, outside the submitted work. PJH reports grants from the Wellcome Trust and Medical Research Council, during the conduct of the study. The position of AIL at the University of Oxford is funded by Big Health Ltd. AIL reports non-financial support and other from Big Health Ltd, during the conduct of the study, and personal fees, non-financial support, and other from Big Health Ltd, outside the submitted work. CHi reports grants from Roche and Eli Lilly, outside the submitted work. AG reports grants from NIHR HTA Grant Number 13/15/04, outside the submitted work. PK reports research grant funding from NIHR and the Economic and Social Research Council. SJ reports research grant funding from NIHR outside the submitted work. PK is Vice President of the British Psychological Society. AMG reports grants from NIHR Maudsley Biomedical Research Centre, outside the submitted work, and is writing a book on sleep to be published by Bloomsbury Sigma. AMG has provided guidance and educational content for the Pediatric Sleep Council website ; a freely available educational website providing tips to help with sleep in babies and young children. The website is partially supported by Johnson and Johnson, but they do not have any influence over content and do not advertise on it. AMG contributes to the British Broadcasting Corporation Focus magazine. CAE is a co-founder and Chief Medical Officer of the digital cognitive behavioural therapy for an insomnia programme (Sleepio/Big Health Ltd) and reports other from Big Health Ltd, during the conduct of the study, and other from Big Health Ltd and personal fees from Warnford Wellness, outside the submitted work. CAE has a US patent issued: serial number 14/172,347, Interactive System for Sleep Improvement; docket number HAME-001. All other authors declare no competing interests.
© 2017 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license