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.

DOI: 10.1016/S2215-0366(17)30328-0

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@inproceedings{Freeman2017TheEO, title={The effects of improving sleep on mental health (OASIS): a randomised controlled trial with mediation analysis}, author={Daniel Freeman and Bryony Sheaves and Guy M. Goodwin and Ly-Mee Yu and Alecia Nickless and Paul J. Harrison and Richard Emsley and Annemarie I Luik and Russell G. Foster and Vanashree Wadekar and Christopher Alan Hinds and Andrew I. Gumley and Ray B. Jones and Stafford Lightman and Steve Jones and Richard P . Bentall and Peter Kinderman and Georgina Rowse and Traolach S. Brugha and Mark T. Blagrove and Alice M. Gregory and Leanne Fleming and Elaine Walklet and Cris Glazebrook and E Bethan Davies and Chris Hollis and Gillian Haddock and Bev John and Mark Coulson and David Fowler and Katherine Pugh and John Cape and Peter Moseley and Gary P Brown and Claire Hughes and Marc C Obonsawin and Sian E Coker and Edward Watkins and Matthias Schwannauer and Kenneth M A Macmahon and Aloysius Niroshan Siriwardena and Colin A Espie}, booktitle={The lancet. Psychiatry}, year={2017} }