Kitajima Tsuyoshi

AIM: Sleep disturbance, a core feature of bipolar disorder, is closely associated with mood symptoms. We examined the association between actigraphy sleep parameters and mood episode relapses in patients with bipolar disorder. METHODS: This prospective cohort study analyzed 193 outpatients with bipolar disorder who participated in the Association between the Pathology of Bipolar Disorder and Light Exposure in Daily Life (APPLE) cohort study. The participants' sleep was objectively evaluated via actigraphy over 7 consecutive days for the baseline assessment and then at the 2-year follow-up appointment for mood episode relapses. The actigraphy sleep parameters were presented using the mean and variability (standard deviation) of each sleep parameter for 7 days. RESULTS: Of the 193 participants, 110 (57%) experienced mood episodes during follow-up. The participants with higher variability in total sleep time had a significantly shorter mean estimated time to mood episode relapses than those with lower variability (12.5 vs. 16.8 months; P < 0.001). The Cox proportional hazards model, when adjusted for potential confounders, demonstrated that variability in total sleep time was significantly associated with an increase in the mood episode relapses (per hour; hazard ratio [HR], 1.407; 95% confidence interval (CI), 1.057-1.873), mainly in the depressive episodes (per hour; HR, 1.477; 95% CI, 1.088-2.006). CONCLUSIONS: Our findings suggest that consistency in sleep time might be useful, as an adjunct therapy, in preventing the recurrence or relapse of mood episodes in bipolar disorder. This article is protected by copyright. All rights reserved.

BACKGROUND: Circadian activity rhythm disruption is a core feature in bipolar disorder. We investigated whether light exposure in daily life is associated with circadian activity rhythms in patients with bipolar disorder. METHODS: In a cross-sectional study, we enrolled 194 outpatients with bipolar disorder who were participants of the Association between Pathology of Bipolar Disorder and Light Exposure in Daily Life (APPLE) cohort study. The participants' physical activity and daytime illuminance were measured using an actigraph over 7 consecutive days. Nighttime illuminance in the bedroom was measured using a portable photometer. Circadian activity rhythm parameters were calculated using cosinor analysis and a nonparametric circadian rhythm analysis. RESULTS: The median daytime illuminance and nighttime illuminance were 224.5 lx (interquartile range, 154.5-307.5 lx) and 2.3 lx (0.3-9.4 lx), respectively. Multivariable linear regression analysis, adjusted for potential confounding factors, showed that higher daytime illuminance was significantly associated with higher amplitude and most active continuous 10-hour period, advanced acrophase, higher interdaily stability, and lower intradaily variability. Higher nighttime illuminance was significantly associated with lower relative amplitude, delayed onset of the least active continuous 5-hour period, and higher intradaily variability. LIMITATIONS: As this was a cross-sectional study, the results do not necessarily imply that light exposure alters circadian activity rhythms. CONCLUSIONS: Daytime light exposure was associated with a positive effect and nighttime light exposure with a negative effect on circadian activity rhythms in bipolar disorder.

OBJECTIVES: The influence of habitual alcohol consumption on insomnia symptoms in healthy workers remains unclear. In this study, we evaluated the association between habitual alcohol consumption among civil servants and insomnia symptoms such as difficulty falling asleep, difficulty staying asleep, and tiredness after sleep, using longitudinal data. METHODS: We enrolled civil servants in a prospective cohort study who completed questionnaires at baseline. Of those, 2861 participants were revaluated in a 5-year follow-up survey. Insomnia symptoms during the past month were assessed using self-reporting. Alcohol drinking habits were assessed by querying the frequency of drinking alcohol as well as the amount of alcohol usually consumed per one occasion. RESULTS: Drinking alcohol every day was less likely to have difficulty falling asleep (odds ratio, 0.42 95% confidence interval, 0.20-0.89), and drinking alcohol 3 or more days a week was associated with difficulty staying asleep (odds ratio, 1.48; 95% confidence interval, 1.16-1.90). CONCLUSIONS: Drinking alcohol every day may produce subjective improvement in sleep onset. However, drinking alcohol 3 or more days a week may increase arousal during sleep, which contributes to reduced sleep quality. These results suggest the possibility that long-term daily habitual drinking may reinforce a sense of improvement in subjective sleep onset but may possibly induce sleep disturbance.