Changes in subjective excessive daytime sleepiness after the Great East Japan Earthquake

Abstract

Introduction We have investigated the degree of subjective excessive daytime sleepiness (EDS) in Japanese visitors to our homepage, which explains about snoring, since 2009. The Great East Japan Earthquake occurred on 11 March 2011, and resulted in more than 20,000 people dying or going missing. The aim of this study is to examine changes in EDS after the Great East Japan Earthquake. Materials and methods The subjects were visitors to our homepage between 12 March and 3 June, both in 2010 and 2011, and 20 years old or older. The exclusion criteria were sedative hypnotic use, antiallergic agents use, previous diagnosis of sleep apnea, and time in bed (TIB) of less than 3 h or 9 h or more. Visitors before the earthquake (over 12 weeks in 2010) constituted the control group. Visitors after the earthquake (over 12 weeks in 2011) were assigned to 6 groups according to when they visited our homepage (2-week intervals over the 12-week period). We compared adjusted mean Epworth Sleepiness Scale (ESS) scores between groups through analysis of covariance (ANCOVA) with the following variables: gender, age, BMI, snoring frequency, being informed of having apnea (e.g. by a spouse), dry feeling in the pharynx at waking, night-time nasal obstruction, nocturia frequency, difficulty falling asleep, and time in bed. Results The characteristics of the subjects before the earthquake (n = 474) and after the earthquake (n = 426) were: male (63% vs. 65%), mean age (39 vs. 39 years old), mean BMI (23.7 vs. 23.8 kg/m2), mean ESS (8.3 vs. 8.1 score), mean TIB (6.4 vs. 6.3 h), mean nocturia frequency (0.31 vs. 0.35/night), requiring 30 min or more to fall asleep (4.2% vs. 5.4%), snoring once a week or more (88% vs. 89%), and being informed of having apnea (47% vs. 51%), respectively. Adjusted mean ESS scores differed significantly between the control group and visitors 5–6 weeks after the earthquake (8.5 vs. 6.6 score, respectively; P Conclusion The group of Japanese visitors to our homepage 5–6 weeks after the earthquake had the lowest degree of EDS. This might be related to insomnia due to stress from the earthquake and its aftermath. Acknowledgements All members of the Department of Psychosomatic Medicine, Kyushu University Hospital.