Search

Yu Itoh,1 Masahiro Takeshima,1 Yoshitaka Kaneita,2 Naohisa Uchimura,3 Yuichi Inoue,4 Makoto Honda,5 Wataru Yamadera,6 Norio Watanabe,7 Shingo Kitamura,8 Isa Okajima,9 Naoko Ayabe,10 Kyoko Nomura,11 Kazuo Mishima1 1Department of Neuropsychiatry, Akita University Graduate School of Medicine, Akita, Japan; 2Division of Public Health, Department of Social Medicine, Nihon University School of Medicine, Tokyo, Japan; 3Department of Neuropsychiatry, Kurume University, Fukuoka, Japan; 4Department of Somnology, Tokyo Medical University, Tokyo, Japan; 5Sleep Disorders Project, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan; 6Division of Bioregulatory Medicine, Department of Katsushika Medical Center, The Jikei University, Tokyo, Japan; 7Health Promotion and Human Behavior, School of Public Health, Kyoto University Graduate School of Medicine, Kyoto, Japan; 8Department of Sleep-Wake Disorders, National Institute of Mental Health, National Center of Neurology and Psychiatry, Tokyo, Japan; 9Department of Psychological Counseling, Faculty of Humanities, Tokyo Kasei University, Tokyo, Japan; 10Department of Regional Studies and Humanities, Faculty of Education and Human Studies, Akita University, Akita, Japan; 11Department of Environmental Health Science and Public Health, Akita University Graduate School of Medicine, Akita, JapanCorrespondence: Kazuo MishimaDepartment of Neuropsychiatry, Akita University Graduate School of Medicine, Hondo 1-1-1, Akita, 010-8543, JapanTel +81-18-884-6122Fax +81-18-884-6445Email mishima@med.akita-u.ac.jpPurpose: Large-scale natural disasters have an enormous physical and mental impact, immediately after they occur, on people living near the central disaster areas. It is known that, in the early stages, a seismic disaster triggers high rates of symptoms for insomnia, depression, and anxiety. However, little information is available about their medium- to long-term clinical outcomes. In this study, we conducted a repeated cross-sectional nationwide questionnaire survey to clarify changes in the prevalence of insomnia and its background factors after the Great East Japan Earthquake, a huge earthquake with a moment magnitude of 9.0 that occurred on March 11, 2011.Methods: We conducted a repeated cross-sectional survey in November 2009 (pre-earthquake, 1224 participants), July 2011 (4 months post-earthquake, 1259 participants), and August 2012 (18 months post-earthquake, 1289 participants) using stratified random sampling from 157 Japanese sites.Results: Compared to 2009, the prevalence of insomnia statistically increased nationwide immediately post-disaster (11.7% vs 21.2%; p < 0.001) but significantly decreased in 2012 compared to immediately after the earthquake (10.6% vs 21.2%; p < 0.001). In 2011, insomnia was most frequent in the central disaster area. Multivariable logistic regression models demonstrated the association between the following factors and increased risk of insomnia: being a woman (odds ratio [OR] 1.48, 95% confidence interval [CI]: 1.00– 2.19), being employed in 2009 (OR 1.74, 95% CI: 1.15– 2.62), and being of younger age group (20– 64 years) in 2011 (OR 1.64, 95% CI: 1.12– 2.42) and 2012 (OR 2.50 95% CI: 1.47– 4.23). Post-earthquake, the prevalence of insomnia symptoms in men increased, while the gender difference decreased and was no longer statistically significant. Additionally, insomnia was associated with psychological distress (scores ≥ 5 on the Kessler Psychological Distress Scale) in 2011 and 2012.Conclusion: This study demonstrated that the prevalence of insomnia was significantly higher after the earthquake. Moreover, individuals with insomnia were more likely to experience psychological distress after the earthquake that continued until 2012.Keywords: disaster, earthquakes, insomnia, psychological stress