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.


Introduction
A tremendous number of studies have been reported on Posttraumatic stress disorder (PTSD), especially in the last decade.

Disasters and PTSD
An epidemiological study was performed on a total of 271 adolescents who had been evacuated from their homes 3 months after Typhoon Morakot in Taiwan (Young et al., 2011).The prevalence of PTSD related to the typhoon was 25.8% and adolescents with PTSD had more severe depression and internalizing, externalizing, social, thought and attention problems than those without PTSD (Young et al., 2011).Even 4 years after the Parnitha earthquake in Greece, 22% of survivors reported subjective distress and intense fear during the earthquake and participation in rescue operations positively correlated with greater post-earthquake psychological stress (Livanou et al., 2004).The psychological consequence of earthquakes may be serious and long-lasting even when the magnitude of the earthquake is moderate (Livanou et al., 2004).
At .5 and 3 years after a severe earthquake (7.3 on the Richter scale) in Taiwan, the estimated rate of victims with posttraumatic stress symptoms (PTSS) was 23.8% and 4.4%, respectively, and PTSS scores were tightly correlated with QOL scores (with less severe symptoms linking to higher QOL) (Tsai et al., 2007).

PTSD Related to Combat and Violence
In 20 Vietnam veterans diagnosed with combat-related PTSD, urine collections in three 8 hours (8:00-16:00, 16:00-24:00, 24:00-8:00) to measure catecholamine levels showed that noradolenergic activity was undiminished at night and sleep was disturbed in comparison with 8 non-combat-exposed controls (Mellman et al., 1995).In the case of victims of violent crimes with PTSD, posttraumatic nightmares and insomnia improved and daytime PTSD symptom severity was reduced after a single, 90 min intervention which used cognitive-behavioral techniques aimed at reducing post-traumatic nightmares and insomnia (Germain et al., 2007).

Circadian Typology and Sleep Habits
Morningness-Eveningness preference shows the phase relationship of circadian clocks to the environmental zeitgebers and * Corresponding author.

PTSD, Sleep Disturbance and Circadian Typology
Sleep disturbance is one of 4 factors indicating PTSD symptoms as assessed by the Impact Event Scale-Revised (IES-R) and the main symptom exhibited in PTSD (Germain et al., 2005;Mellman, 2008;Wang, 2011).However, there have been no studies on the relationship between PTSD symptoms and circadian typology.This study tries to examine this relationship from an epidemiological point of view.

Questionnaire Study
An integrated questionnaire was administered to 467 people aged 38 -92 (mean age: 64.8 years) in Hyogo Prefecture (35˚N), Japan in August 2011, with responses received from 223 people (females: 142, males: 78, unknown: 3) which were all usable for analysis.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 (1980) and a Japanese version (Kasugai, 1998) of the Impact of Event Scale-Revised (IES-R) which has been usually used as PTSD scores (Wilson & Keane, 2004) composed of 22 questions, 8 questions related to intrusion, 6 on hyper-arousal and 8 on avoidancenumbing (Table 1).The original questions on sleep habits which Harada et al. (1998) originally constructed have been used in several papers (Takeuchi et al., 2001a;Takeuchi et al., 2001b;Harada et al., 2002;Takeuchi et al., 2003;Harada et al., 2004;Shinomiya et al., 2004;Harada et al., 2007).

Statistical Analysis
The data was statistically analyzed using Mann-Whitney U-tests and Pearson's correlation analysis with SPSS 20.0 statistical software.Diurnal Type scale scores were expressed as means plus or minus the standard deviation (Mean ± SD).

Criterion for High and Low Damage Groups
Participants were divided into a High Damage Group (HDG) and a 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 (Table 2).The criterion for the HDG and LDG was more than 100 dead persons or more than 1000 buildings collapsed completely.According to this criterion, participants living in the 7 districts of Higashinada, Nada, Chuo, Hyogo, Nagata, Suma and Tarumi were included in HDG and those in Nishi and Kita were in the LDG (Table 2).
The study followed the guidelines established by the Chronobiology International Journal for the conduct of research on human subjects (Portaluppi et al., 2010).Before administrating the questionnaires, each participant was given a written explanation that detailed the concepts and purposes of the study and stated that their answers would be used only for academic purposes.After the above explanation, all participants agreed completely with the proposal.The study was also permitted by the ethic committee in the Laboratory of Environmental Physiology, Graduate School of Integrated Arts and Sciences, Kochi University which carried out an ethical inspection of the contents of the questionnaire

Results
PTSD scores (21.9 points on average) were significantly higher in the High Damage Group (HDG) than those (17.1) in the Low Damage Group (LDG) (Mann-Whitney U-test: z = −2.270,p = .02)(Figure 1).Scores of HDG participants tended Table 1.Examples of questions of the Impact of Event Scale-Revised (IES-R) (Wilson & Keane, 2004).

One example of 8 questions on avoidance-numbing Q:
How extent do you avoid something to make you remember the disaster?

One example of 8 questions on intrusion Q:
How extent do something on the disaster appear suddenly in your brain?
A: (0) Never, (1) a little, (2) medium, (3) much, (4) extreme One example of 6 questions on hyper-arousal Q: Are you enough nervous to be in high tension triggered with a small thing?
Only in HDG participants, there was a significant 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]) (Pearson's correlation test: r = −.353,p = .001in HDG; r = .010,p = .920in LDG) (Figure 2).
In both HDG and LDG, there was a significantly positive correlation between the Subjective Sleep Quality Scale (higher score meaning lower sleep quality) and the IES-R scores (higher PTSD scores correlated with lower quality of sleep) (r = .536,p < .001 in HDG; r = .319,p = .001in LDG) (Figure 3).

Discussion
Even 17 years after the Hanshin-Awaji Great Earthquake (magnitude: 7.3), PTSD symptoms due to the earthquake remains.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.This study is the first to indicate a positive correlation between evening-typed lifestyle and PTSD symptoms (morning-type lifestyle and reduced PTSD symptoms).
What are the mechanisms underlying this relationship?Three hypothetical pathways are possible.The first is that dreaming during REM sleep consolidates the memorizing system in the brain (Karni et al., 1994;Hornung et al., 2007) and may delete the scarce memory of the earthquake.The second is via a high amount of serotonin synthesis in the morning due to a richprotein breakfast (Harada et al., 2007;Nakade et al., 2009Nakade et al., , 2012)).Diminished 5-HT 2A recepter signaling in the brain appears to be associated with the cognitive syndrome observed in PTSD and certain subgroups of depressive illness (Van Praag, 2004a, 2004b).Therefore, a higher amount of serotonin synthesis in the pineal gland could compensate, partially, the shortage of 5-HT 2A receptors.The third possible mechanism is better inner synchronization of the main and slave clocks (Honma & Honma, 1988) shown by morning-type people whose clocks are well entrained to zeitgebers such as light, temperature and social cues.The second and third pathways can both improve mental health (Takeuchi et al., 2002;Harada, 2008;Harada et al., 2012) and this improvement could reduce the symptoms of PTSD.However, these hypotheses remain to be tested in the future.Intervention to improve their quality of sleep and promote a morning-typed lifestyle may be an effective way to reduce PTSD symptoms.

Conclusion and Limitation
This study could imply the shifting to "morning-typed life" Copyright © 2013 SciRes.might reduce the symptoms of PTSD for the victims who suffered from great disaster.The limitation of this study is that the questionnaire study cannot say the causal relationship between morning-typology and reduced PTSD.Some experimental study for the causal relationship is remained in the future.

H
Figure 1.Comparison of current (Aug 2011) PTSD scores of participants of a High Damage Group (HDG) and a Low Damage Group (LDG) of the Hanshin-Awaji Great Earthquake (Jan 1995).
Figure 2. Negative correlation between current scores of Diurnal Type scale scores and PTSD scores which was shown only for participants in a High Damage Group (HDG) of the Hanshin-Awaji Great Earthquake even after 17 years after the disaster.↑Worse