Background: Insomnia has a high prevalence in modern society. Various tools have been developed to assess insomnia. We performed a direct comparison between the Insomnia Severity Index (ISI) and the Athens Insomnia Scale (AIS) in a Japanese population. Methods: A cross-sectional questionnaire-based study was conducted in September 2017 as part of the Night in Japan Home Sleep Monitoring Study. In addition to insomnia, assessed using the AIS and ISI, depression, sleepiness, quality of life, and work performance were assessed using the Patient Health Questionnaire (PHQ)-9, a Japanese version of the Epworth Sleepiness Scale, the Short Form-8 Health Survey Questionnaire (SF-8), and the World Health Organization Health and Work Performance Questionnaire, respectively. Receiver operating characteristic (ROC) curves were constructed to compare the outcomes of the AIS and the ISI. Results: A total of 1685 (81.9%) of all eligible employees were enrolled. The total scores of the AIS and ISI had a Pearson correlation coefficient (r) of 0.80 (p < 0.01). The area under the ROC curve for the AIS and ISI for the detection of depression (PHQ-9 ≥ 10) was 0.89 and 0.86, respectively. The prevalence of clinical insomnia (ISI ≥ 15) and definite insomnia (AIS ≥ 10) were 6.5 and 10.8%, respectively. Both the AIS and ISI showed a weak negative correlation with the physical component summary score of the SF-8 (r = − 0.37, p < 0.01 and r = − 0.32, p < 0.01, respectively) and absolute presenteeism (r = − 0.32, p < 0.01 and r = − 0.28, p < 0.01, respectively) and a moderate negative correlation with the mental component summary score of the SF-8 (r = − 0.53, p < 0.01 and r = − 0.43, p < 0.01, respectively). Conclusions: A strong positive correlation was found between the total scores of the AIS and ISI. Both the AIS and ISI were found to be associated with low physical and mental quality of life, depression, and productivity loss at work. Moreover, they had a moderate accuracy for detecting depression. Both the AIS and ISI may serve as useful screening tools for both insomnia and depression in the Japanese working population. Trial registration: UMIN-CTR (UMIN000028675, registered on 2017/8/15) and ClinicalTrials.gov (NCT03276585, registered on 2017/9/3).

Background:The present study aimed to analyze the association among depression, sleep quality, and quality of life using the Japanese version of the Structured Clinical Interview for DSM-IV Axis I Disorders Non-Patient Edition (SCID-I/NP), and to compare these findings with those obtained using self-reported scales, in an urban male working population in Japan. Methods: The present study included 324 middle-aged participants (43.8 ± 8.37 years) (participation rate: 69.5%). The Japanese version of the SCID-I/NP was administered by a single physician. Self-reported scales, including the Zung SelfRating Depression Scale (SDS), Epworth Sleepiness Scale (ESS), Pittsburgh Sleep Quality Assessment (PSQI), and 36-item Short-Form Health Survey (SF-36) were used to assess depression, sleepiness, sleep quality, and quality of life, respectively. Participants were then divided into a major depressive disorder (MDD) and control group based on the results of structured interviews, following which self-reported scale scores were compared between the two groups. Results: A total of 24 participants met criteria for MDD based on responses during structured interviews (current: 4; past: 20). Patients with MDD did not report feeling sleepier than those without psychiatric disorders (controls) (ESS: P = 0.184), although they experienced slightly poorer sleep quality (PSQI: P = 0.052). In addition, participants of the MDD group exhibited lower SF-36 subscale scores for general health (P = 0.002), vitality (P < 0.001), social functioning (P < 0.001), role emotional (P = 0.004), and mental health (P < 0.001) domains, and higher SDS scores (P = 0.038) compared to controls. The area under the receiver (AUC) operating characteristic curve for the detection of MDD was 0.631 and 0.706 for the SDS and mental health subscales, respectively. Conclusions: Our findings indicate that patients with MDD exhibit slightly poorer sleep quality and significantly poorer quality of life compared to controls, and that the SF-36 may be used as an alternative to the SDS to screen for depression in an urban male working population in Japan.

Narcolepsy without cataplexy (NA w/o CA) (narcolepsy type 2) is a lifelong disorder characterized by excessive daytime sleepiness and rapid eye movement (REM) sleep abnormalities, but no cataplexy. In the present study, we examined the human leukocyte antigen HLA-DQB1 in 160 Japanese patients with NA w/o CA and 1,418 control subjects. Frequencies of DQB1*06:02 were significantly higher in patients with NA w/o CA compared with controls (allele frequency: 16.6 vs. 7.8%, P=1.1×10−7, odds ratio (OR)=2.36; carrier frequency: 31.3 vs. 14.7%, P=7.6×10−8, OR=2.64). Distributions of HLA-DQB1 alleles other than DQB1*06:02 were compared between NA w/o CA and narcolepsy with cataplexy (NA-CA) to assess whether the genetic backgrounds of the two diseases have similarities. The distribution of the HLA-DQB1 alleles in DQB1*06:02-negative NA w/o CA was significantly different from that in NA-CA (P=5.8×10−7). On the other hand, the patterns of the HLA-DQB1 alleles were similar between DQB1*06:02-positive NA w/o CA and NA-CA. HLA-DQB1 analysis was also performed in 186 Japanese patients with idiopathic hypersomnia (IHS) with/without long sleep time, but no significant associations were observed.

Background: This descriptive study was conducted to examine the changes in the symptom frequency in patients with rapid eye movement (REM) sleep behavior disorder (RBD) without medical intervention, in order to determine the association of RBD symptom frequency with disease duration. Methods: Data were collected from 70 consecutive RBD patients who visited the Sleep Clinic in Shiga University of Medical Science. RBD symptom frequencies at the first visit to the clinic were quantified based on the reports by the patients and their family members. For quality assurance, patients living alone or those with cognitive decline were excluded. Finally, 50 patients with family-confirmed symptom history were enrolled. The symptom frequencies were converted to a unit that reflects the estimated number of nights in a year affected by RBD (NAR). Using NAR, we observed the relation between RBD symptom frequency and the disease duration. Results: Of the 50 patients, 41 were male and 9 were female, consistent with the male-dominant nature of this disease. The mean age at RBD onset was 62.2 ± 9.1 years, and the mean disease duration at the time of visit was 6.0 ± 4.9 years. The median symptom frequency was 50 NAR, with a 1st quantile value of 24 NAR and a 3rd quantile value of 115 NAR. When RBD symptom frequency was plotted against disease duration, we found that the frequency was lowest in the first 2 years of RBD (median, 18; range, 2-29 NAR), and higher frequencies were found in 2-year bin groups from 2 to 8 years after RBD onset (median, 60; range,. Intriguingly, after 8 years of RBD, the frequency returned to a level comparable to that in the first 2 years of RBD (median, 50; range, 12-100 NAR). Conclusions: There was no association between RBD symptom frequency and disease duration. RBD clinical symptoms could be less prominent when neural damage becomes severe. Therefore, a natural decrease in RBD symptom frequency may be indicative of progression of neurodegeneration.

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