Implications for Social Support on Prolonged Sleep Difficulties among a Disaster-Affected Population: Second Report from a Cross-Sectional Survey in Ishinomaki, Japan

STUDY OBJECTIVES: This study aimed to investigate the role of social factors, especially social support for sleep, among victims living at home around 1–2 years after the Great East Japan Earthquake and tsunami. DESIGN: A cross-sectional household survey was conducted between May and December 2012 (14–21 months after the disaster) in the Ishinomaki area, Japan. Univariate and multivariate logistic regression models were used to examine the association between social factors, including social support, and prolonged sleep difficulties (persisting over 1 month). Social support was divided into three functions: emotional, informational, and instrumental support. PARTICIPANTS: Data were obtained on 2,593 individuals who were living at home after the disaster. RESULTS: The prevalence of prolonged sleep difficulties was 6.9% (5.8% male, 7.7% female). This study showed that lack of social support has a stronger association with prolonged sleep difficulties than non-modifiable or hardly modifiable consequences caused directly by the disaster, i.e., severity of home damage, change in family structure and income. Among the three dimensions of social support, lack of emotional support showed the strongest association with prolonged sleep difficulties. CONCLUSIONS: Social support, especially emotional support, may positively affect sleep among victims living at home around 1–2 years after a disaster.