Bidirectional associations between post-traumatic stress symptoms and sleep quality among older survivors of the 2011 Great East Japan Earthquake and Tsunami

• Published in: Sleep (New York, N.Y.) Vol. 46; no. 6; p. 1
• Main Authors: Yazawa, Aki, Shiba, Koichiro, Okuzono, Sakurako Shiba, Hikichi, Hiroyuki, Kawachi, Ichiro
• Format: Journal Article
• Language: English
• Published: US Oxford University Press 13.06.2023
• Subjects: 2011 AD; Analysis; Disaster victims; Disease susceptibility; Earthquakes; Editor's Choice; Epidemiology; Humans; Insomnia and Psychiatric Disorders; Japan; Japan - epidemiology; Post-traumatic stress disorder; Sleep; Sleep disorders; Sleep Quality; Sleep Wake Disorders; Stress Disorders, Post-Traumatic - epidemiology; Survivors; Tsunamis; Japan; Epidemiology; Post-Traumatic Stress Disorder (PTSD); Gerontology
• ISSN: 0161-8105; 1550-9109
• DOI: 10.1093/sleep/zsad106

Abstract Study Objectives We sought to examine the bidirectional associations between post-traumatic stress symptoms (PTSS) and sleep quality in a sample of older disaster survivors. Methods We used 4 waves (2010, 2013, 2016, and 2020) of the Iwanuma Study, which included pre-disaster information and 9 years of follow-up data among older survivors of the 2011 Great East Japan Earthquake and Tsunami. Poisson regression analysis was used to examine the bidirectional associations between sleep problems and PTSS. Results Individuals reporting sleep problems before the disaster were more likely to develop PTSS after exposure to disaster trauma, while there was no effect modification, i.e. prevalence ratio for sleep problems did not differ by the magnitude of disaster damages. Individuals reporting sleep problems after the disaster were less likely to recover from PTSS, and more likely to develop the delayed onset of PTSS 5 years after the disaster. While individuals who recovered from PTSS 9 years after the disaster were still at slightly higher risk of having sleep problems compared to those who never had PTSS, none of the sleeping problems were found to be significantly prevalent after the Bonferroni correction. Conclusions Pre-disaster sleep problems predicted PTSS onset independently of experiences of disaster trauma. The association between PTSS and sleep problems was bidirectional. Intervening to mitigate lingering sleep problems may benefit the recovery of disaster survivors from post-traumatic symptoms. Graphical Abstract Graphical Abstract