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Original Articles
Introduction
Subjective reports of various types of sleep disturbance are described in all phases of bipolar disorder (BD), including remission (Harvey et al. 2005; Harvey, 2008; Kaplan et al. 2011; Kanady et al. 2015; Ng et al. 2015) but with substantial variability in prevalence between studies. Meta-analyses of studies objectively estimating sleep variables in remitted BD patients demonstrated prolonged total sleep time (TST), increased wakenings after sleep onset greater variability of sleep-wake variables and reduced sleep efficiency (Geoffroy et al. 2014; Ng et al. 2015). These meta-analyses highlighted that there has also been little consistency in the way sleep and circadian rhythm has been measured and assessed. Studies have used a range of actiwatches and algorithms for calculating sleep and wake estimates and utilized variable recording periods, making comparisons across studies challenging. There is a need for methodological improvements, including longer recordings to allow improved analysis of circadian rhythm measures. Thus it is currently unknown what proportion of sleep disorder relates to a circadian rhythm disorder (CRD). Furthermore, none of the published actigraphy studies in BD have performed respiratory sleep studies to screen for primary sleep disorders, such as obstructive sleep apnoea (OSA), that may additionally contribute to hypersomnia and sleep fragmentation. The aim of this study was to describe the different sleep-wake phenotypes in an opportunistic cohort of patients with BD and age-matched healthy controls with a comprehensive battery of objective and subjective assessments of sleep and circadian variables, including urinary melatonin levels and respiratory sleep studies analysis.
Method
Participants
The study was approved by the National Research Ethics Service Committee North East - Newcastle & North Tyneside. Outpatients with BD type I or II, in any mood state, were recruited from a research database, patient support groups, and NHS services in the North East of England. Healthy controls, matched by age and gender, were recruited from Newcastle University, local volunteer databases and hospital staff and their families. All participants provided written informed consent before taking part in the research. Participants were aged 18-65 years, fluent in English and able to provide consent. Exclusion criteria were: verbal IQ <90 assessed with the National Adult Reading Test (NART; Nelson, 1982), any significant medical...