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

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Freeman, Daniel; Sheaves, Bryony; Goodwin, Guy M; Yu, Ly-Mee; Nickless, Alecia; Harrison, Paul J; Emsley, Richard; Luik, Annemarie I; Foster, Russell G; Wadekar, Vanashree; Hinds, Christopher; Gumley, Andrew; Jones, Ray; Lightman, Stafford; Jones, Steve; Bentall, Richard; Kinderman, Peter; Rowse, Georgina; Brugha, Traolach; Blagrove, Mark; Gregory, Alice M.; Fleming, Leanne; Walklet, Elaine; Glazebrook, Cris; Davies, E Bethan; Hollis, Chris; Haddock, Gillian; John, Bev; Coulson, Mark; Fowler, David; Pugh, Katherine; Cape, John; Moseley, Peter; Brown, Gary; Hughes, Claire; Obonsawin, Marc; Coker, Sian; Watkins, Edward; Schwannauer, Matthias; MacMahon, Kenneth; Siriwardena, A Niroshan and Espie, Colin A. 2017. The effects of improving sleep on mental health (OASIS): a randomised controlled trial with mediation analysis. The Lancet Psychiatry, 4(10), pp. 749-758. ISSN 2215-0366 [Article]

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Official URL: https://doi.org/10.1016/S2215-0366(17)30328-0

Abstract or Description

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.

Item Type:

Article

Identification Number (DOI):

https://doi.org/10.1016/S2215-0366(17)30328-0

Additional 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.