Nonrestorative sleep and its association with insomnia severity, sleep debt, and social jetlag in adults: Variations in relevant factors among age groups.

OBJECTIVE: Nonrestorative sleep (NRS) is unrefreshing sleep that is harmful to mental and physical health. Although few studies have reported the relationship between NRS and sleep problems, none have evaluated this relationship by age group. This study aimed to determine whether NRS could be associated with insomnia severity, sleep debt, and social jetlag and whether this relationship would vary with age. METHODS: The 1592 participants were allocated into age groups: 18-25 years (n = 317), 26-40 years (n = 405), 41-65 years (n = 454), and >65 years (n = 416). The study used Restorative Sleep Questionnaire to assess NRS, Athens Insomnia Scale to assess insomnia severity, Sleep Debt Index to assess sleep debt, and the absolute difference in midpoints of sleep between weekdays and days off to assess social jetlag. RESULTS: Logistic regression analysis was performed to determine the association between NRS and sleep problems. In the 18-25-year group, insomnia severity, sleep debt of ≥2 h, and social jetlag of ≥2 h; in the 26-40-year group, insomnia severity and sleep debt of ≥2 h; in the 41-65-year group, insomnia severity and sleep debt of ≥2 h; and in the >65-year group, insomnia severity were significantly associated with NRS. CONCLUSION: NRS was associated with insomnia severity in all age groups, with sleep debt in the young and working-age groups and social jetlag in the young age group. Different approaches to improving the NRS are required for different age groups.

Psychometric properties of the Japanese version of the Insomnia Catastrophizing Scale and relationship of insomnia severity with catastrophic thoughts, safety behaviors, and dysfunctional beliefs.

BACKGROUND: This study aimed to clarify the reliability and validity of the Japanese version of the Insomnia Catastrophizing Scale (ICS) and to examine the relationship between insomnia severity and insomnia-related cognitive factors. METHODS: A total of 786 participants were recruited via an online survey and classified into the insomnia group (n = 342) and healthy group (n = 444). The insomnia group comprised individuals who self-reported meeting the diagnostic criteria for chronic insomnia disorder in the third edition of the International Classification of Sleep Disorders. RESULTS: The ICS is used to independently assess nighttime (ICS-N) and daytime (ICS-D) catastrophic thoughts, and item response theory revealed that each ICS-N and ICS-D item can adequately assess catastrophic thoughts during the night and day, respectively. The internal consistency and test-retest reliability of the ICS-N and ICS-D were good. Further, the ICS-N and ICS-D had a significant positive correlation with insomnia severity, hyperarousal, sleep-related safety behaviors, dysfunctional beliefs about sleep, and anxiety symptoms. Multiple regression analyses with insomnia severity as the dependent variable in the insomnia group demonstrated that catastrophic thoughts were more strongly associated with insomnia severity than sleep-related safety behaviors and dysfunctional beliefs about sleep. The interaction between nighttime catastrophic thoughts and sleep-related safety behaviors increased insomnia severity. CONCLUSIONS: The Japanese versions of ICS-N and ICS-D were found to be superior in measuring insomnia-related catastrophic thoughts and to have high reliability and validity. Furthermore, these findings more clearly demonstrate that the catastrophic thoughts may be an important associated factor of insomnia.

Effect of cognitive behavioral therapy for insomnia in workers: A systematic review and meta-analysis of randomized controlled trials.

Although cognitive behavioral therapy for insomnia (CBT-I) is recommended as a first-line treatment, its efficacy for workers with insomnia remains unclear. This systematic review and meta-analysis aimed to determine the effectiveness of CBT-I in the management of insomnia symptoms in workers. We searched the literature in three electronic databases, namely PubMed, PsycINFO, and Embase, and included 21 studies in the meta-analysis. Compared with the control group, CBT-I overall resulted in significant improvements in terms of severity of insomnia (g = -0.91), sleep onset latency (g = -0.62), wakefulness after sleep onset (g = -0.60), early morning awakening (g = -0.58), and sleep efficiency (g = 0.71). However, there was no improvement in the total sleep time relative to that in the control group. Furthermore, CBT-I significantly alleviated depressive (g = -0.37) and anxiety (g = -0.35) symptoms and fatigue (g = -0.47) compared with the control group. Our study findings suggest that both web-based and face-to-face CBT-I are effective interventions for managing insomnia symptoms in daytime workers, although it is important to note that only face-to-face CBT-I achieved clinically meaningful changes. The effectiveness of CBT-I for shift workers could not be determined.

Network analysis to estimate central insomnia symptoms among daytime workers at-risk for insomnia.

Although insomnia complaints are associated with mental health problems and reduced work productivity, the central insomnia symptoms in workers at-risk for insomnia remain unclear. This study aimed to identify the central insomnia symptoms among daytime workers at risk for insomnia. The participants were 881 Japanese daytime workers at-risk for insomnia with a mean age of 49.33 ± 9.92 years. At-risk for insomnia was defined as an Athens Insomnia Scale score of six or higher. The Athens Insomnia Scale was used as a screening for at-risk insomnia because it has higher sensitivity and specificity than other insomnia screening scales. The Insomnia Severity Index is recommended as a mechanism of insomnia and an outcome measure; therefore, a network analysis was conducted with the seven items of the Insomnia Severity Index. The important variables in the connections between insomnia symptoms were estimated from centrality indices, which were interpretable only for strength. The strength value results suggest that difficulty staying asleep and worry about sleep problems were the central insomnia symptoms. The connections were stronger for difficulty staying asleep and problem waking up too early, difficulty staying asleep and difficulty falling asleep, and interference with daytime functions and noticeable to others. Worry about sleep problems was strongly associated with variables other than nocturnal insomnia symptoms. Therefore, difficulty staying asleep and worry about sleep problems are important variables in daytime workers at-risk for insomnia and are key points for improvement or exacerbation of insomnia symptoms.

Development and validation of the Japanese version of the Restorative Sleep Questionnaire in community samples.

OBJECTIVE: This study aimed to validate the Japanese version of the Restorative Sleep Questionnaire Weekly version (RSQ-W-J) and estimate the RSQ-W-J cut-off score to identify the degree of non-restorative sleep (NRS) that interferes with daytime function. METHODS: An online survey was conducted, and 513 participants (241 men, 272 women; mean age, 47.88 ± 16.66 years) completed the questionnaires. The RSQ-W-J, Multidimensional Fatigue Inventory, Athens Insomnia Scale, Patient Health Questionnaire-9, Epworth Sleepiness Scale, Sleep Debt Index, NRS and the degree of daytime dysfunction, and the diagnostic criteria for chronic insomnia were used as implementation scales. RESULTS: The RSQ-W-J was confirmed to have a single-factor structure. Both the Cronbach α coefficient and test-retest reliability of RSQ-W-J were high (α = 0.91; intraclass correlation coefficient [ICC]agreement = 0.85). The RSQ-W-J was significantly negatively correlated with the scales of fatigue, insomnia, depressive symptoms, daytime sleepiness, and sleep debt. In addition, the RSQ-W-J scores of the insomnia group, in which participants met the diagnostic criteria for chronic insomnia, NRS group, in which participants had NRS only, and sleep debt group, in which participants had sleep debt, were significantly lower than those in the normal sleep group. Furthermore, the insomnia group scored significantly lower than the sleep debt group. The RSQ-W-J cut-off score, which indicates whether or not NRS interferes with daytime function, was estimated to be 45.8 points. CONCLUSIONS: The RSQ-W-J was shown to be useful for comprehensively measuring the degree of restorative sleep.

Association between insomnia severity and presenteeism among Japanese daytime workers.

Presenteeism is the loss of productivity due to a worker's health problems, despite the worker being present at the workplace. Although the association between presenteeism and insomnia complaints is well known, few studies have examined the association between insomnia severity and presenteeism. This study aimed to explore the association between insomnia severity and presenteeism. This study included 1925 participants (1543 males, 379 females, and three of other genders) in total. The mean age of the participants was 49.94 ± 9.82 years. The inclusion criteria were full-time employment, working 8 hr per day and 5 days per week, and having no night shifts. The insomnia severity was classified based on the Insomnia Severity Index and Athens Insomnia Scale criteria. Logistic regression analysis showed that moderate and severe insomnia severity were associated to a greater magnitude with presenteeism than mild insomnia severity. Severe insomnia severity was associated to a greater magnitude with presenteeism than moderate insomnia severity. In summary, logistic regression analysis showed that increased insomnia severity based on Insomnia Severity Index classification was associated with increased odds of presenteeism, but increased insomnia severity based on Athens Insomnia Scale classification was not fully consistent with increased odds of presenteeism. Because increased insomnia severity is associated with worsening of presenteeism, early detection of and early intervention against insomnia complaints are important for reducing presenteeism. This study was the first to examine the associations between presenteeism and insomnia severity classification of no insomnia, mild, moderate, and severe insomnia severity.

Impact of sleep debt, social jetlag, and insomnia symptoms on presenteeism and psychological distress of workers in Japan: a cross-sectional study.

BACKGROUND: Presenteeism is an indicator of productivity loss and the risk of absence from work due to mental health problems. The purpose of this study was to determine the impact of sleep debt, social jetlag, and insomnia symptoms on presenteeism and psychological distress. METHODS: The participants were 351 Japanese workers (271 males, 79 females, and one of other gender, with a mean age of 49 ± 9.49 years). The eligibility criteria for this study were full-time employment, working eight hours per day, five days per week, and no night shifts. The participants answered questionnaires measuring sleep debt, social jetlag, insomnia symptoms, presenteeism, and psychological distress. RESULTS: Insomnia symptoms had the greatest impact on presenteeism and psychological distress when compared with sleep debt and social jetlag (adjusted odds ratio (OR) = 5.61, 95% confidence interval (CI) = 2.88-10.91; adjusted OR = 7.29, 95%CI = 3.06-17.35). Sleep debt had a greater impact on presenteeism and psychological distress than did social jetlag (adjusted OR = 1.61, 95%CI = 1.14-2.27; adjusted OR = 1.68, 95%CI = 1.11-2.54), which had no impact on these variables (adjusted OR = 1.04, 95%CI = 0.91-1.20; adjusted OR = 0.96, 95%CI = 0.76-1.22). CONCLUSIONS: The findings of this study indicated that insomnia symptoms had a more significant impact on presenteeism and psychological distress than social jetlag and sleep debt. Although sleep debt might have an independent impact on presenteeism and psychological distress, social jetlag did not.