Development and validation of the Japanese version of the Hyperarousal Scale

The objectives of this study were to develop a Japanese version of the Hyperarousal Scale (HAS-J) and investigate its factor structure, reliability, and validity, as well as to calculate a cutoff score for the HAS-J and assess different levels of hyperarousal in insomnia patients and community dwellers.

We recruited 224 outpatients receiving insomnia treatment (56.3% women; mean age 51.7 ± 15.6 years) and 303 community dwellers aged 20 years or older (57.8% women; mean age 43.9 ± 15.2 years). Exploratory and confirmatory factor analysis was performed to examine the factor structure of the HAS-J. Cronbach's α and McDonald's ω were then used to test internal consistency. To examine the scale's validity, we determined correlations between the HAS-J and other indexes and compared HAS-J scores between insomnia patients and community dwellers. We also compared HAS-J scores between two community-dweller groups (normal and poor sleepers) and two insomnia patient groups (with and without alleviation after treatment).

Following exploratory and confirmatory factor analysis, a 20-item measure emerged comprising three factors: "Introspectiveness and Reactivity," "Neuroticism," and "Insomnia." Confirmatory factor analysis showed a generally good fit for the model of the three-factor structure suggested by the exploratory factor analysis loadings (χ² (163) = 327.423, (p <  0.001), CFI = 0.914, GFI = 0.872, AGFI = 0.835, RMSEA = 0.067). In insomnia patients, internal consistency indicated sufficient reliability of the HAS-J. Correlation analysis showed weak to moderate positive correlations of the HAS-J score with other indexes, indicating concurrent validity of the HAS-J. All HAS-J subscale scores were significantly higher in insomnia patients than in community dwellers. Additionally, the total score in patients with alleviation of insomnia was comparable to that in poor sleepers and significantly higher than that in normal sleepers.

This study demonstrated the reliability and validity of the HAS-J, indicating that it is useful as a clinical scale of hyperarousal. The high level of hyperarousal in insomnia patients who were assessed to be in remission by the Insomnia Severity Index suggests a risk of insomnia recurrence in these patients.