PTSD Score, Circadian Typology and Sleep Habits of People who Experienced the Great Hanshin-Awaji Earthquake 17 Years Ago

This study aims to determine the relationship between Post Traumatic Stress Disorder (PTSD) and current circadian typology and sleep habits of adults who experienced the Great Hanshin-Awaji Earthquake (on 17th January 1995) after becoming adults. An integrated questionnaire was administered in August, 2011 to 467 people aged 38 92 (mean age: 64.8 years) in Hyogo Prefecture, Japan, with responses received from 223 people (females: 142, males: 78, unknown: 3). The questionnaire consisted of basic questions about attributes such as age and sex, questions on sleep habits and sleep quality (Subjective Sleep Quality Scale), the Torsvall-Åkerstedt Diurnal Type Scale and the Impact of Event Scale-Revised (IES-R) which dealt with PTSD scores. The participants were divided into a High Damage Group (HDG) and Low Damage Group (LDG) based on public statistical information on the extent of damage to buildings and number of casualties in the smaller districts of Kobe City in which participants experienced the disaster. HDG participants exhibited significantly higher IES-R scores than LDG participants (p = .002). Only in HDG participants, there was significantly negative correlation between Diurnal-Type scale scores and IES-R scores (high PTSD scores correlated with greater evening type [low scores of Diurnal-Type scale]) (p = .001) (p = .920 in LDG participants). In both the HDG and LDG, there was a significant positive correlation between the Subjective Sleep Quality Scale (higher score meaning lower sleep quality) and IES-R score (high PTSD scores correlated with low quality of sleep) (p < .001 in HDG; p = .001 in LDG). These results suggest that people who suffered severe damage from a disaster and who currently show severe PTSD symptoms are more evening-typed and have a lower quality of sleep. Intervention to improve their quality of sleep and promote a morning-typed lifestyle may be an effective way to reduce PTSD symptoms.