Nonrestorative sleep

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.

Sleep Health Analysis Through Sleep Symptoms in 35,808 Individuals Across Age and Sex Differences: Comparative Symptom Network Study

BACKGROUND

Sleep health is a multidimensional construct that includes objective and subjective parameters and is influenced by individual sleep-related behaviors and sleep disorders. Symptom network analysis allows modeling of the interactions between variables, enabling both the visualization of relationships between different factors and the identification of the strength of those relationships. Given the known influence of sex and age on sleep health, network analysis can help explore sets of mutually interacting symptoms relative to these demographic variables.

OBJECTIVE

This study aimed to study the centrality of symptoms and compare age and sex differences regarding sleep health using a symptom network approach in a large French population that feels concerned about their sleep.

METHODS

Data were extracted from a questionnaire provided by the Réseau Morphée health network. A network analysis was conducted on 39 clinical variables related to sleep disorders and sleep health. After network estimation, statistical analyses consisted of calculating inferences of centrality, robustness (ie, testifying to a sufficient effect size), predictability, and network comparison. Sleep clinical variable centralities within the networks were analyzed by both sex and age using 4 age groups (18-30, 31-45, 46-55, and >55 years), and local symptom-by-symptom correlations determined.

RESULTS

Data of 35,808 participants were obtained. The mean age was 42.7 (SD 15.7) years, and 24,964 (69.7%) were women. Overall, there were no significant differences in the structure of the symptom networks between sexes or age groups. The most central symptoms across all groups were nonrestorative sleep and excessive daytime sleepiness. In the youngest group, additional central symptoms were chronic circadian misalignment and chronic sleep deprivation (related to sleep behaviors), particularly among women. In the oldest group, leg sensory discomfort and breath abnormality complaint were among the top 4 central symptoms. Symptoms of sleep disorders thus became more central with age than sleep behaviors. The high predictability of central nodes in one of the networks underlined its importance in influencing other nodes.

CONCLUSIONS

The absence of structural difference between networks is an important finding, given the known differences in sleep between sexes and across age groups. These similarities suggest comparable interactions between clinical sleep variables across sexes and age groups and highlight the implication of common sleep and wake neural circuits and circadian rhythms in understanding sleep health. More precisely, nonrestorative sleep and excessive daytime sleepiness are central symptoms in all groups. The behavioral component is particularly central in young people and women. Sleep-related respiratory and motor symptoms are prominent in older people. These results underscore the importance of comprehensive sleep promotion and screening strategies tailored to sex and age to impact sleep health.

Insomnia Symptoms and Environmental Disruptors: A Preliminary Evaluation of Veterans in a Subacute Rehabilitation

OBJECTIVES

Evaluate insomnia symptoms and environmental disruptors at admission and discharge in a subacute rehabilitation care setting.

METHODS

Veterans (age ≥50) admitted to a Veterans Health Administration (VA) Hospital subacute rehabilitation between March and August 2022 completed baseline (N = 46) and follow up (N = 33) assessments with the Insomnia Severity Index (ISI), Sleep Need Questionnaire (SNQ), Epworth Sleepiness Scale (ESS), and an assessment of environmental sleep disruptors. Veterans were offered sleep resources after admission evaluations and outpatient referrals after discharge evaluations. Pearson correlation determined associations between length of stay (LOS), ISI, SNQ, and ESS scores at admission and discharge; chi-square and Wilcoxon Signed Rank Tests compared insomnia at admission and discharge.

RESULTS

One-half of participants reported clinically meaningful insomnia symptoms and sleep needs at baseline with no significant change at discharge. Almost all (89.1%) Veterans reported sleep was disturbed by environmental factors, primarily staff awakenings. LOS was correlated with ESS scores at discharge (r = .52, p = .002).

CONCLUSIONS

Environmental sleep disruption was common during a subacute rehabilitation admission and were not adequately addressed through sleep resources and treatment due to low uptake.

CLINICAL IMPLICATIONS

Providers should assess sleep at admission and lessen environmental sleep disruptors by reducing noise, light, and non-essential awakenings at night.

Nonrestorative Sleep and Type 2 Diabetes Incidence: the Aichi Workers' Cohort Study

BACKGROUND

The term "nonrestorative sleep (NRS)" refers to unrefreshed feeling at wake-up and is a domain of poor sleep quality. Previous researches have demonstrated that NRS is linked to a number of diseases and adverse health outcomes, but less is known regarding the link between NRS and diabetes, particularly in Japanese.

METHODS

We studied 3665 middle-aged male participants of the Aichi Workers' Cohort Study who were followed-up from 2002 to 2019. Cox proportional hazards models estimated hazard ratios (HRs) and 95% confidence intervals (CIs) of incident type 2 diabetes mellitus (T2DM) in relation to NRS adjusted for potential confounding variables.

RESULTS

During a median follow-up of 14.6 years, 421 type 2 diabetes cases were identified. Participants with NRS had a higher crude incidence rate of T2DM (11.2/1,000 person-years), compared to participants without NRS (9.3/1,000 person-years). In the fully adjusted model, individuals who reported having NRS had a significantly higher risk of developing T2DM (HR: 1.36, 95% CI: 1.10-1.67). The association was observed only in participants under 50 years old (HR: 1.82, 95% CI: 1.36-2.43), not in the older (50 years or older) participants (P for interaction =0.025). In contrast, stratified analyses by the presence of shift work, obesity or sleep duration showed similar associations in all the strata.

CONCLUSIONS

NRS was associated with higher risk of T2DM in middle-aged Japanese male workers independent of a variety of lifestyle factors and other sleep problems.

Impact of chronotype, insomnia symptoms, sleep duration, and electronic devices on nonrestorative sleep and daytime sleepiness among Japanese adolescents

OBJECTIVES

Nonrestorative sleep (NRS) and excessive daytime sleepiness (EDS) are important indicators of daytime dysfunction. Electronic media use before bedtime greatly affects adolescent sleep quality. However, few studies have examined factors associated with these symptoms. Therefore, we aimed to investigate the impact of chronotype, electronic device use before bedtime, and insomnia symptoms on NRS and EDS in Japanese adolescents.

METHODS

A web-based cross-sectional survey of 2067 adolescents was conducted in 2022 to mainly assess sleep-related issues (sleep duration, chronotype, insomnia symptoms, NRS, and EDS), time spent using electronic devices, physical activity, and mental health.

RESULTS

We analyzed data of 1880 adolescents (age, 16.4 ± 0.8 years; males, 56.7%). NRS and EDS prevalence rates were 54.9% and 39.4%, respectively. In multivariate analysis, evening chronotype [odds ratio (OR): 2.14, 95% confidence interval (CI): 1.58-2.89], difficulty initiating sleep (OR: 1.94, 95% CI: 1.43-2.64), <5 h sleep (OR: 1.77, 95% CI: 1.24-2.54), 5-6 h sleep (OR: 1.52, 95% CI: 1.20-1.93), and using electronic devices just before bedtime (OR: 1.48, 95% CI: 1.08-2.04) were associated with NRS. Evening chronotype (OR: 1.40, 95% CI: 1.07-1.82), early morning awakening (OR: 1.60, 95% CI: 1.02-2.50), using electronic devices just before bedtime (OR: 2.08, 95% CI: 1.48-2.93), and using electronic devices 30 min before bedtime (OR: 1.57, 95% CI: 1.07-2.29) were associated with EDS.

CONCLUSION

Chronotype may be an important factor influencing NRS and EDS. Discontinuing electronic device use at least 30 min before bedtime could benefit affected adolescents.

The REM microarousal and REM duration as the potential indicator in paradoxical insomnia

OBJECTIVE

Although paradoxical insomnia is a prevalent subtype of chronic insomnia, the etiology of it is unclear. Contrary to complaints of little or no sleep, polysomnography (PSG) findings show that paradoxical insomnia patients have near normal sleep macrostructure. The purpose of this study is to determine the changes of microstructure and explore the etiology of paradoxical insomnia.

METHODS

The PSG findings of 89 paradoxical insomnia patients were compared with those of 41 gender balanced healthy controls without sleep complaints. All subjects underwent nocturnal PSG recordings. Conventional PSG measures and microarousals were quantified and statistically analyzed. Receiver operating characteristic curve and correlation analysis were used to evaluate the potential of REM sleep microarousals and REM duration as indicators of paradoxical insomnia.

RESULTS

Compared with the controls, paradoxical insomnia patients had no significant differences in sleep macrostructures. Statistical analysis showed that non-rapid eye movement (NREM) microarousals revealed no significant differences between paradoxical insomnia patients and controls. Noticeably, more spontaneous microarousals appeared in rapid eye movement (REM) stage for paradoxical insomnia patients. Based on receiver operating characteristic curve (ROC), the optimal cutoff value of REM sleep microarousals could predict paradoxical insomnia. Furthermore, a positive correlation between microarousals in REM sleep and the duration of REM sleep was presented in paradoxical insomnia patients.

CONCLUSIONS

The frequency of REM microarousals and the duration of REM sleep could reflect the real sleep state of paradoxical insomnia patients. That suggested PSG investigation extended to microarousal could be helpful to understand the etiology in paradoxical insomnia.

The effect of nonrestorative sleep on incident hypertension 1-2 years later among middle-aged Hispanics/Latinos

BACKGROUND

Insomnia is known to be a major risk factor for incident hypertension. Nonrestorative sleep (NRS), which refers to insufficiently rested sleep, has reported to associate with various diseases. This study aimed to investigate the longitudinal association between insomnia-related symptoms including NRS and incident hypertension 1-2 years later by age group (young, 18-39 years and middle-age, 40-64 years) using existing cohort data involving Hispanics/Latinos.

METHODS

This study included 1100 subjects who had participated in both the Hispanic Community Health Study/Study of Latinos and its follow-up study, the Sueño Ancillary Study, and met additional eligibility criteria. Incident hypertension was assessed by self-reported history and/or the use of antihypertensives. The Women's Health Initiative Insomnia Rating Scale (WHIIRS) was used to evaluate insomnia-related symptoms (difficulty initiating sleep, difficulty maintaining sleep, early morning awakening, difficulty returning to sleep, and NRS). Logistic regression analyses were conducted to assess the degree to which insomnia-related symptoms at baseline predicted incident hypertension.

RESULTS

Among the participants (64% middle-aged, 36% young adults), 140 (12.7%) developed hypertension during the follow-up period. Among the sleep-related symptoms, only NRS predicted incident hypertension after adjusting for sociodemographic factors and physical condition (odds ratio: 1.88, 95% confidence interval: 1.10-3.21, p = 0.022) in middle-aged adults. None of the insomnia-related symptoms were associated with incident hypertension in the young adults. No association was found between WHIIRS-defined insomnia (total score ≥ 9) and incident hypertension in middle-aged adults or young adults.

CONCLUSION

The present findings suggest the importance of focusing on NRS to help prevent the development of hypertension in middle-aged adults.

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.

The association between sleep quality and telomere length: A systematic literature review

Several sleep parameters present an elevated risk for processes that contribute to cellular aging. Short sleep duration, sleep apnoea, and insomnia are significantly associated with shorter telomeres, a biological marker of cellular aging. However, there has been no review or analysis of studies that have examined the association between the psychological construct of sleep quality and telomere length. The present study aimed to provide a systematic review of the association between sleep quality and telomere length. A systematic review of English articles was conducted using MEDLINE/PubMed, PsycINFO, Google Scholar, and Web of Science electronic databases, with the final search conducted on 3rd September 2021. Search terms included sleep quality, poor sleep, insomnia, sleep difficulties, sleep issue*, non-restorative sleep, telomere*, cellular aging, and immune cell telomere length. Study eligibility criteria included human participants aged 18 years or older and a reproducible methodology. Study appraisal and synthesis were completed using a systematic search in line with a PICOS approach (P = Patient, problem, or population; I = Intervention, prognostic factor, exposure; C = Comparison, control, or comparator; O = Outcomes; S = Study designs). Twenty-two studies met review inclusion criteria. Qualitative synthesis of the literature indicated insufficient evidence overall to support a significant association between sleep quality and telomere length. Limitations across studies were addressed, such as the assessment of examined constructs. Findings highlight important targets for future research, including the standardised operationalisation of the sleep quality construct and experimental study designs. Research in this area has clinical significance by identifying possible mechanisms that increase the risk for age-related disease and mortality. PROSPERO Registration No.: CRD 42021233139.

Longitudinal assessment of lifestyle factors associated with nonrestorative sleep in Japan

OBJECTIVE

Nonrestorative sleep (NRS) is common in the general global population. This study surveyed the incident/remission rate of NRS and identified related lifestyle factors in a general Japanese adult cohort.

METHODS

Data from a Japanese health check-based cohort between the fiscal years 2011 and 2018 were obtained. NRS was assessed through a single item question, and socio-demographic and clinical data were assessed through self-reports. To identify potential correlates of NRS incidence/remission, Cox regression analysis (or survival analysis) was performed.

RESULTS

Among the 135 609 individuals surveyed at baseline, data from 93 548 were considered for analysis. NRS exhibited incidence and remission rates of 11.3% and 15.4%, respectively. New NRS incidence was predicted by eating fast (hazard ratio [HR]: 1.07, 95% confidence interval [CI]: 1.04-1.10), dining close to bedtime (HR: 1.33, 95% CI: 1.27-1.38), midnight snacking (HR: 1.09, 95% CI: 1.04-1.13), skipping breakfast (HR: 1.16, 95% CI: 1.10-1.22), non-regular exercise (HR: 1.12, 95% CI: 1.07-1.17), lower levels of physical activity (HR: 1.19, 95% CI: 1.14-1.24), and slow walking speed (HR: 1.34, 95% CI: 1.29-1.39), while heavy drinking was less predictive of NRS. However, the same factors (except for heavy drinking) were found to predict NRS remission.

CONCLUSIONS

We found that unhealthy lifestyle behaviors, particularly dining close to bedtime and slow walking speed, were positively associated with NRS incidence, while they were negatively associated with NRS remission. These results can be useful in developing more effective health promotion policies to achieve good sleep.

Associations among Alcohol Drinking, Smoking, and Nonrestorative Sleep: A Population-Based Study in Japan

Nonrestorative sleep (NRS) is a common sleep disorder. It is associated with several unhealthy lifestyle factors, such as skipping breakfast and lack of exercise. However, the associations between alcohol drinking, smoking, and NRS are unclear. This study examined the prevalence of NRS within the Japanese general population and the relationships among alcohol drinking, smoking, and NRS. We analyzed an anonymized dataset from a 2013 nationwide population survey (35,717 men and 39,911 women). NRS was assessed through a single-item question, and socio-demographic and lifestyle factors were assessed through self-reports. Multivariable logistic regression analyses were used to examine the associations between alcohol drinking, smoking, and NRS. The total prevalence of NRS was 22.2% (95% CI 21.8-22.7) in men and 23.4% (95% CI 23.0-23.8) in women. Further, we found that sleep duration and prevalence of NRS shared an inverse J-shaped relationship. Heavy alcohol drinking was significantly associated with NRS in both sexes. Short sleep duration and certain socioeconomic factors modified the effect of smoking on NRS in men. These results could be useful in the development of more effective sleep health policies to establish better sleep hygiene.

Sleep Continuity, Sleep Related Daytime Dysfunction, and Problem Endorsement: Do These Vary Concordantly by Age?

OBJECTIVES

Sleep continuity (i.e., ability to initiate and/or maintain sleep) worsens with age. It is unclear whether problem endorsement and/or daytime dysfunction show similar age-related trends. Accordingly, a large archival dataset was used to examine age differences in sleep continuity, problem endorsement, and sleep related daytime dysfunction.

METHOD

Participants were categorized as: Young Adults (18-29 years); Adults (30-44 years); Middle Aged Adults (45-64 years); and Older Adults (65-89 years). Young Adults, Adults, and Middle Aged Adults were 1:1 matched with Older Adults (n = 233) on the basis of gender, race, ethnicity, and BMI. MANOVA, ANOVAs, and chi-square analysis were performed to assess for age-related differences.

RESULTS

In a sample of 932 adults with self-reported sleep continuity disturbance (i.e., insomnia), sleep continuity was significantly worse in older age groups. This effect was limited to middle and late insomnia with middle aged and older adults waking up with greater frequency and for longer durations of time during the night and in the early morning than younger cohorts. Problem endorsement largely increased across age groups (except for sleep latency) but reports of overall sleep-related daytime dysfunction showed no difference by age.

CONCLUSION

When evaluating sleep continuity disturbance, assessing whether the patient identifies their sleep continuity disturbance as a problem and whether it affects their daytime function can be informative, particularly in older adults. It may serve to reveal (case-by-case) when there are discordances between incidence/severity of illness and problem endorsement/daytime dysfunction. Such information may better inform if treatment should be initiated.

Transient oscillation dynamics during sleep provide a robust basis for electroencephalographic phenotyping and biomarker identification

Transient oscillatory events in the sleep electroencephalogram represent short-term coordinated network activity. Of particular importance, sleep spindles are transient oscillatory events associated with memory consolidation, which are altered in aging and in several psychiatric and neurodegenerative disorders. Spindle identification, however, currently contains implicit assumptions derived from what waveforms were historically easiest to discern by eye, and has recently been shown to select only a high-amplitude subset of transient events. Moreover, spindle activity is typically averaged across a sleep stage, collapsing continuous dynamics into discrete states. What information can be gained by expanding our view of transient oscillatory events and their dynamics? In this paper, we develop a novel approach to electroencephalographic phenotyping, characterizing a generalized class of transient time-frequency events across a wide frequency range using continuous dynamics. We demonstrate that the complex temporal evolution of transient events during sleep is highly stereotyped when viewed as a function of slow oscillation power (an objective, continuous metric of depth-of-sleep) and phase (a correlate of cortical up/down states). This two-fold power-phase representation has large intersubject variability-even within healthy controls-yet strong night-to-night stability for individuals, suggesting a robust basis for phenotyping. As a clinical application, we then analyze patients with schizophrenia, confirming established spindle (12-15 Hz) deficits as well as identifying novel differences in transient non-rapid eye movement events in low-alpha (7-10 Hz) and theta (4-6 Hz) ranges. Overall, these results offer an expanded view of transient activity, describing a broad class of events with properties varying continuously across spatial, temporal, and phase-coupling dimensions.

A Nationally Representative Survey Assessing Restorative Sleep in US Adults

Restorative sleep is a commonly used term but a poorly defined construct. Few studies have assessed restorative sleep in nationally representative samples. We convened a panel of 7 expert physicians and researchers to evaluate and enhance available measures of restorative sleep. We then developed the revised Restorative Sleep Questionnaire (REST-Q), which comprises 9 items assessing feelings resulting from the prior sleep episode, each with 5-point Likert response scales. Finally, we assessed the prevalence of high, somewhat, and low REST-Q scores in a nationally representative sample of US adults (n= 1,055) and examined the relationship of REST-Q scores with other sleep and demographic characteristics. Pairwise correlations were performed between the REST-Q scores and other self-reported sleep measures. Weighted logistic regression analyses were conducted to compare scores on the REST-Q with demographic variables. The prevalence of higher REST-Q scores (4 or 5 on the Likert scale) was 28.1% in the nationally representative sample. REST-Q scores positively correlated with sleep quality (r=0.61) and sleep duration (r=0.32), and negatively correlated with both difficulty falling asleep (r=-0.40) and falling back asleep after waking (r=-0.41). Higher restorative sleep scores (indicating more feelings of restoration upon waking) were more common among those who were: ≥60 years of age (OR=4.20, 95%CI: 1.92-9.17); widowed (OR=2.35, 95%CI:1.01-5.42), and retired (OR=2.02, 95%CI:1.30-3.14). Higher restorative sleep scores were less frequent among those who were not working (OR=0.36, 95%CI: 0.10-1.00) and living in a household with two or more persons (OR=0.51,95%CI:0.29-0.87). Our findings suggest that the REST-Q may be useful for assessing restorative sleep.

Association of insomnia symptoms and non-restorative sleep with Typus melancholicus: a Japanese general population survey

This study aimed to investigate the association between insomnia symptoms and non-restorative sleep (NRS) in individuals with Typus melancholicus, a personality trait linked to depression, in the general population. We analyzed data from a Japanese cross-sectional survey of 2519 randomly sampled adults. Typus melancholicus was evaluated using a modified version of Kasahara's Typus melancholicus inventory (modified-KTM). Logistic regression analysis was used to examine the associations of insomnia symptoms and NRS with modified-KTM scores. We demonstrated that insomnia symptoms and NRS were both positively associated with modified-KTM scores. Our results provide evidence for an association between Typus melancholicus and insomnia.

Associations of nonrestorative sleep and insomnia symptoms with incident depressive symptoms over 1-2 years: Longitudinal results from the Hispanic Community Health Study/Study of Latinos and Sueño Ancillary Study

BACKGROUND

Nonrestorative sleep (NRS), defined as insufficiently rested or refreshed sleep, is considered to play an important role in the development of depression. The aim of this study is to investigate the predictive ability of insomnia-related symptoms, including NRS, for incident depressive symptoms (DEPs) in a longitudinal manner.

METHODS

We used data of 1196 samples aged 18-64 years who participated in both the Hispanic Community Health Study/Study of Latinos conducted in 2008-2010 and the follow-up study (Sueño Ancillary Study) conducted in 2010-2013. DEPs and insomnia-related symptoms (difficulty initiating sleep [DIS], difficulty maintaining sleep [DMS], early morning awakening [EMA], difficulty returning to sleep [DRS], and NRS) were evaluated by the 10-item Center for Epidemiologic Studies Depression Scale and the Women's Health Initiative Insomnia Rating Scale, respectively. A logistic regression analysis was used to evaluate the predictive ability of each insomnia-related symptom at baseline for incident DEPs in couple-years.

RESULTS

In the univariate logistic regression analysis, all insomnia-related symptoms had significant associations with incident DEPs (DIS, odds ratio [OR] = 1.6; DMS, OR = 1.6; EMA, OR = 1.5; DRS, OR = 1.9; NRS, OR = 2.5). After adjusting for sociodemographic factors and the confounding effects of other insomnia-related symptoms, only NRS (OR = 2.2, 95% confidence interval = 1.4-3.5, p = .001) was significantly associated with incident DEPs.

CONCLUSIONS

NRS was a risk factor for incident DEPs, which includes a predictive ability for other insomnia-related symptoms. Our results suggest that focusing on NRS is an effective strategy for preventing depression in public health promotions.

Differences between subjective and objective sleep duration according to actual sleep duration and sleep-disordered breathing: the Nagahama Study

STUDY OBJECTIVES

Since subjective sleep duration (SSD) is considered to be longer than objective sleep duration (OSD), results of SSD minus OSD (SSD-OSD) might always be thought to be positive. Some recent reports showed different results, but exact results have not been obtained. The difference between SSD and OSD may change according to OSD. We investigated this difference and its association with sleep-disordered breathing (SDB) or nonrestorative sleep.

METHODS

This cross-sectional study evaluated 6,908 community residents in Nagahama, Japan. SSD was determined by self-administered questionnaire. OSD was measured by wrist actigraphy and sleep diary. SDB was assessed according to the 3% oxygen desaturation index adjusted for OSD.

RESULTS

Worthy of notice was that SSD was shorter than OSD for those with SSD longer than 6.98 hours in all participants, 7.36 hours in males, and 6.80 hours in females. However, SSD was longer than OSD (mean ± SD: 6.49 ± 1.07 vs 6.01 ± 0.96; P < .001) overall, as SSD is considered to be longer than OSD. In patients with SDB, the difference between SSD-OSD was greater when OSD was shorter. The difference also depended on SDB severity. The degree of positivity between OSD and SSD was a significant factor in nonrestorative sleep (odds ratio: 2.691; P < .001).

CONCLUSIONS

When OSD was slightly less than 7 (6.98) hours, participants reported or perceived SSD > OSD. When OSD was > 6.98 hours, participants reported or perceived SSD < OSD. Patients with SDB reported longer SSD than OSD according to severity of SDB. Evaluating SSD, OSD, and their differences may be useful for managing sleep disturbances, including nonrestorative sleep.

CITATION

Takahashi N, Matsumoto T, Nakatsuka Y, et al. Differences between subjective and objective sleep duration according to actual sleep duration and sleep-disordered breathing: the Nagahama Study. J Clin Sleep Med. 2022;18(3):851-859.

Insomnia Severity and Degree of Dysfunction: What Is to Be Learned When These Domains are Discordant?

OBJECTIVE/BACKGROUND

Illness severity and resultant dysfunction are often linearly related and tightly coupled (concordant). Some percentage of individuals, however, exhibit discordant associations (high illness severity and low dysfunction [HL] or low illness severity and high dysfunction [LH]). In the present study, a sample of subjects with insomnia complaints were evaluated to determine what percentage of subjects exhibited discordant associations.

PARTICIPANTS

Archival data were drawn from a community-based sample (n = 4,680; 61.8% female; Ages 18-105).

METHODS

Median splits were calculated for illness severity and daytime dysfunction and each individual was typed as High (H) or Low (L) for the concordant (HH and LL) and discordant domains (HL and LH).

RESULTS

Given this typology, 61% were classified as concordant and 39% were classified as discordant. Of these, 38% were sub-typed as HH, 23% as LL, 26% as LH, and 13% as HL.

CONCLUSIONS

We propose that some of the discordance may be ascribable to a mismatch between sleep need and sleep ability. Those "who need a lot, may suffer a lot, in the face of only a little (LH)", whereas those "who need a little, may suffer only a little, in the face of a lot (HL)".

Measurement properties of the simplified Chinese version of Nonrestorative Sleep Scale in adolescents

This study aimed to assess the measurement properties of a simplified Chinese version of the Nonrestorative Sleep Scale (NRSS) among adolescents. We obtained a simplified Chinese NRSS by the standard forward-backward translation procedures and administered it to 486 students who were attending Grade 7-11 in Nanjing, China. Furthermore, Pittsburgh Sleep Quality Index, Athens Insomnia Scale, Centre for Epidemiological Studies Depression Scale, and Toronto Hospital Alertness Test were also self-completed for measuring sleep quality, insomnia, depression and alertness respectively. The sample was randomly split into two halves, with the first half used to explore the scale structure by exploratory factor analysis (EFA), and the second half used to confirm the identified structure by confirmatory factor analysis (CFA). A total of 481 adolescents (49% male) with a mean age of 16 years (range: 13-18) completed this study. In the other half of 250 adolescents, the root mean square error of approximation (RMSEA), standardised root mean square residual, and comparative fit index (CFI) in CFA, which tested the four-factor structure obtained from EFA, were 0.062, 0.051 and 0.975, respectively. Convergent validity was demonstrated from a significant correlation of the simplified Chinese NRSS with sleep quality (r = -0.62), insomnia (r = -0.71), depression (r = -0.60) and alertness (r = 0.54). The internal consistency and test-retest reliability for the global scale were 0.83 and 0.86 respectively. Measurement invariance was established between males and females with the changes of both CFI and RMSEA < 0.01. The simplified Chinese NRSS is valid and reliable for measuring NRS among Chinese adolescents.

Circadian preference and sleep quality in healthy controls and psychiatric inpatients with major depressive disorder - An actigraphy study incorporating morning and evening mood assessments

Major depressive disorder (MDD) is frequently accompanied by sleep disturbance. Regarding diurnal preference (chronotype), sleep problems and low mood have been associated with evening orientation. Considering diurnal preference, we investigated subjective restorative value of sleep and actigraphy sleep parameters together with mood assessments twice a day, i.e. in the morning and evening, during weekdays and weekends in MDD psychiatric inpatients and healthy controls (HCs). The restorative value of sleep was higher during the weekend in HC, and bedtimes and risetimes were delayed during the weekend compared to weekdays in HC and MDD. Morning mood affected subjective sleep ratings in both groups, while association with symptom severity (BDI) in MDD remained insignificant. In HC, better evening mood was associated with later bedtimes. Regarding the chronotype in HC, evening orientation was associated with relatively low restorative value of sleep during weekdays, and morning orientation was associated with relatively higher actigraphy sleep efficiency during weekdays compared to weekend. In MDD, an association of evening orientation with later rise times could be observed, while no chronotype dependent effect emerged regarding the restorative value of sleep or sleep efficiency. Our results emphasize that research on sleep in MDD should incorporate weekdays as well as weekends, chronotype assessment, and measures of morning and evening mood, as these can be associated with ratings of the subjective restorative value of sleep (i.e. in our study, better morning mood was associated with higher restorative values), but also with behavioral sleep parameters (i.e. in our study, more positive evening mood was associated with later bedtimes). Potentially, the restorative value of sleep in MDD evening types can be improved by maintaining a regular sleep schedule, which needs to be investigated in an experimental design.

Leisure-Time Physical Activity and General Health Mitigate Effects of Job Demands on Nonrestorative Sleep: CDC National Healthy Worksite Project

OBJECTIVE

We sought to determine if leisure-time physical activity (LTPA) modified the adverse relationship between high job demands and nonrestorative sleep (NRS).

METHODS

We conducted a multivariate logistic regression analysis among workers from the cross-sectional National Healthy Worksite Project (n = 4683) using self-report Likert-Scale data on psychological and physical demands of jobs, LTPA and general health in relation to NRS.

RESULTS

Not engaging in LTPA was associated with NRS for workers with jobs at the lowest or highest levels of the physical demand scale (OR 1.64, 95% CI: 0.96-2.81, OR 2.06, 95% CI: 0.95-4.45; respectively) in comparison to those who met LTPA recommendations. When assessing psychological demands, poor general health was associated with NRS at all levels of the scale independent of LTPA.

CONCLUSIONS

LTPA may reduce NRS for workers with jobs at either extreme of physical demands.

Symptom network analysis of the sleep disorders diagnostic criteria based on the clinical text of the ICSD-3

The third edition of the International Classification of Sleep Disorders (ICSD-3) is the authoritative clinical text for the diagnosis of sleep disorders. An important issue of sleep nosology is to better understand the relationship between symptoms found in conventional diagnostic manuals and to compare classifications. Nevertheless, to our knowledge, there is no specific exhaustive work on the general structure of the networks of symptoms of sleep disorders as described in diagnostic manuals. The general aim of the present study was to use symptom network analysis to explore the diagnostic criteria in the ICSD-3 manual. The ICSD-3 diagnostic criteria related to clinical manifestations were systematically identified, and the units of analysis (symptoms) were labelled from these clinical manifestation diagnostic criteria using three rules ("Conservation", "Splitting", "Lumping"). A total of 37 of the 43 main sleep disorders with 160 units of analysis from 114 clinical manifestations in the ICSD-3 were analysed. A symptom network representing all individual ICSD-3 criteria and connections between them was constructed graphically (network estimation), quantified with classical metrics (network inference with global and local measures) and tested for robustness. The global measure of the sleep symptoms network shows that it can be considered as a small world, suggesting a strong interconnection between symptoms in the ICSD-3. Local measures show the central role of three kinds of bridge sleep symptoms: daytime sleepiness, insomnia, and behaviour during sleep symptoms. Such a symptom network analysis of the ICSD-3 structure could provide a framework for better systematising and organising symptomatology in sleep medicine.

Noise sensitivity associated with nonrestorative sleep in Chinese adults: a cross-sectional study

Background

Nonrestorative sleep is a common sleep disorder with a prevalence ranging from 1.4 to 35%, and is associated with various psychological and physical health issues. Noise exposure and noise sensitivity have been proposed to contribute to nonrestorative sleep. This study aimed to examine the relationships among noise, noise sensitivity, nonrestorative sleep, and physiological sleep parameters in Chinese adults.

Methods

A cross-sectional household survey was conducted with randomly selected Chinese adults based on a frame stratified by geographical districts and types of quarters in Hong Kong. We administered a battery of questionnaires, including the Nonrestorative Sleep Scale, the Weinstein Noise Sensitivity Scale, the ENRICHD Social Support Instrument, the Patient Health Questionnaire, and the Perceived Stress Scale to assess nonrestorative sleep, noise sensitivity, social support, somatic symptoms and stress, respectively. Anxiety and depression were evaluated by the Hospital Anxiety and Depression Scale while sociodemographic and lifestyle characteristics were assessed with an investigator-developed sheet. Nocturnal noise level and physiological sleep parameters were measured during nighttime for a week by noise dosimetry and actigraphy, respectively. A structured multiphase linear regression was conducted to estimate associations.

Results

A total of 500 adults (66.4% female) with an average age of 39 years completed this study. Bivariate regressions showed that age, marital status, occupation, family income, season, exercise, cola and soda consumption, social support, somatic symptoms, stress, depression, noise sensitivity, total sleep time, and awakenings were associated with nonrestorative sleep. In the multivariable analysis, family income, season, exercise, social support, somatic symptoms, stress, and depression remained associated with nonrestorative sleep. Specifically, a one-unit increase of noise sensitivity was associated with 0.08 increase in nonrestorative sleep (95% confidence interval [CI]: 0.01, 0.15, p = 0.023). Nocturnal noise was negatively associated with time in bed (b = − 1.65, 95% CI: − 2.77, − 0.52, p = 0.004), total sleep time (b = − 1.61, 95% CI: − 2.59, − 0.62, p = 0.001), and awakenings (b = − 0.16, 95% CI: − 0.30, − 0.03, p = 0.018), but was not associated with nonrestorative sleep.

Conclusions

Nonrestorative sleep was predicted by noise sensitivity in addition to family income, season, exercise, social support, somatic symptoms, stress, and depression.

The association between nonrestorative sleep and health-related quality of life in Chinese adults: a cross-sectional study

PURPOSE

Sleep problems are prevalent among the general population and can cause various health problems, which may lead to decreased quality of life. However, little is known about nonrestorative sleep and its implications. This study aimed to examine the association between nonrestorative sleep and health-related quality of life (HRQL) in Chinese adults.

METHODS

Data were collected through a cross-sectional study of 500 adults in Hong Kong (66.4% female, average age of 39 years). The Short-Form-12 Health Survey version 2 (SF-12v2), Nonrestorative Sleep Scale (NRSS), Pittsburgh Sleep Quality Index, ENRICHD Social Support Instrument, Patient Health Questionnaire, Perceived Stress Scale, and Hospital Anxiety and Depression Scale were administered. Objective sleep parameters were based on participants' sleep condition over 1 week, as measured using an ActiGraph GT9X Link.

RESULTS

Mean standardized scores for the physical component summary (PCS) and mental component summary (MCS) of the SF-12v2 and the NRSS were 50.33 ± 6.50, 49.00 ± 9.03, and 64.77 ± 12.75, respectively. After adjusting for sociodemographic and lifestyle characteristics, sleep quality, objective sleep parameters, social support, somatic symptoms, stress, anxiety, and depression, NRSS scores were associated with PCS (b = 0.12, 95%CI: 0.06 to 0.18, p < 0.001) and MCS (b = 0.08, 95%CI: 0.02 to 0.15, p = 0.013) scores. Furthermore, associations of NRSS score with PCS as well as MCS scores were stronger in women than in men.

CONCLUSION

Nonrestorative sleep is a potentially modifiable risk factor for poor HRQL. Thus, interventions to relieve or decrease nonrestorative sleep could be beneficial for improving HRQL.

Association between Non-Restorative Sleep and Quality of Life in Chinese Adolescents

To examine non-restorative sleep and its impact on quality of life (QOL) in Chinese adolescents, this cross-sectional study included 2827 students aged 12–20 who were selected from 15 secondary schools in Hong Kong, China. Non-restorative sleep was assessed by a single item, rated on a 0–10 scale: “To what extent did you feel refreshed upon awakening over the past month?”. QOL was evaluated by the World Health Organization Quality of Life Measure—Abbreviated Version Hong Kong Chinese Version. Univariable and multivariable linear mixed-effects regressions were conducted to examine the influence of non-restorative sleep (NRS) on QOL. In the present sample, the mean overall QOL was 13.83, and the extent of feeling refreshed upon awakening was 4.75 on average. In multivariable linear mixed-effects regression, one unit feeling less refreshed upon awakening was associated with 0.37 units of poorer overall QOL after adjusting for age, gender, medical conditions, parental education and occupation, weekly hours of aerobic exercises, smoking and drinking habits. Additionally, adolescents with a significantly poorer overall QOL were more likely to be older, have medical problems, have parents with an educational level of primary school or below, have an unemployed father, engage in less weekly aerobic exercise, and be current smokers or former drinkers. Adolescents who experienced non-restorative sleep had a poorer QOL. Future studies are needed to alleviate non-restorative sleep to improve health outcomes in adolescents.

Nonrestorative sleep scale: a reliable and valid short form of the traditional Chinese version

Purpose

Previous research has suggested the essential unidimensionality of the 12-item traditional Chinese version of the Nonrestorative Sleep Scale (NRSS). This study aimed to develop a short form of the traditional Chinese version of the NRSS without compromising its reliability and validity.

Methods

Data were collected from 2 cross-sectional studies with identical target groups of adults residing in Hong Kong. An iterative Wald test was used to assess differential item functioning by gender. Based on the generalized partial credit model, we first obtained a shortened version such that further shortening would result in substantial sacrifice of test information and standard error of measurement. Another shortened version was obtained by the optimal test assembly (OTA). The two shortened versions were compared for test information, Cronbach’s alpha, and convergent validity.

Results

Data from a total of 404 Chinese adults (60.0% female) who had completed the Chinese NRSS were gathered. All items were invariant by gender. A 6-item version was obtained beyond which the test performance substantially deteriorated, and a 9-item version was obtained by OTA. The 9-item version performed better than the 6-item version in test information and convergent validity. It had discrimination and difficulty indices ranging from 0.44 to 2.23 and − 7.58 to 2.13, respectively, and retained 92% of the test information of the original 12-item version.

Conclusion

The 9-item Chinese NRSS is a reliable and valid tool to measure nonrestorative sleep for epidemiological studies.

Electronic supplementary material

The online version of this article (10.1007/s11136-020-02523-4) contains supplementary material, which is available to authorized users.

Linking Nonrestorative Sleep and Activity Interference Through Pain Catastrophizing and Pain Severity: An Intraday Process Model Among Individuals With Fibromyalgia

Nonrestorative sleep is a key diagnostic feature of the musculoskeletal pain disorder fibromyalgia and is robustly associated with poor physical functioning, including activity interference. However, the mechanisms through which nonrestorative sleep elicits activity interference among individuals with fibromyalgia at the within-person level remain unclear. The present study tested the following 3-path mediation model, using data gathered from a 21-day electronic daily diary in 220 individuals with fibromyalgia: previous night nonrestorative sleep → morning pain catastrophizing → afternoon pain severity → end-of-day activity interference. Results of multilevel structural equation modeling supported the 3-path mediation model. Previous night's nonrestorative sleep and morning pain catastrophizing were also directly related to end-of-day activity interference. Previous night nonrestorative sleep did not significantly predict afternoon pain severity while controlling for the effect of morning pain catastrophizing. Greater nonrestorative sleep during the previous night and a higher level of morning pain catastrophizing appear to serve as risk factors for experiencing greater daily pain and activity interference later in the day. These findings point to the potential utility of targeted interventions that improve both sleep quality and pain catastrophizing to help individuals with chronic pain engage in important daily activities despite experiencing pain. PERSPECTIVE: This study provides a better understanding of how nonrestorative sleep is associated with daily activity interference among individuals with fibromyalgia. An intervention that targets attenuating nonrestorative sleep and pain catastrophizing may help improve daily physical functioning of this population.

Association of sleep quality with telomere length, a marker of cellular aging: A retrospective cohort study of older adults in the United States

BACKGROUND

Sleep quality is a risk factor for age-related diseases, and although the underlying mechanisms remain unclear, the effects of poor sleep quality on telomere length (TL) may play a role.

OBJECTIVE

The objective of the study was to evaluate the independent association between sleep quality and salivary TL in a large sample of older adults.

DESIGN

We adopted a retrospective cohort design, and participants comprised 5,268 adults drawn from the Health and Retirement Study. We used the 2006 (baseline) and 2008 (follow-up) waves. Baseline sleep quality was assessed using 4 Likert scale questions (trouble falling asleep, waking up during the night, waking up too early and not being able to fall sleep again, and feeling well rested in the morning). The TL was assessed using the T/S ratio, a continuous variable. The associations between sleep quality and T/S were assessed using multivariable ordinary least squares regressions. All analyses were adjusted for demographics, lifestyle characteristics, psychosocial, and other factors.

RESULTS

Overall, 16% reported never feeling well rested in the morning; 25.7% of respondents always had trouble waking during the night; and 12.8% always had trouble waking up too early in the morning. Respondents who never felt rested in the morning had significantly shorter TL than those who always felt rested in the morning (adjusted beta = -0.08, standard error = 0.03, P < .01). The composite sleep measure was not significantly associated with shorter TL.

CONCLUSIONS

In this cohort of older adults, not feeling well rested in the morning was significantly and inversely associated with TL; however, the composite measure of sleep quality was not significantly associated with TL. These findings suggest a potential connection between one of the measures of impaired sleep and reduction in TL, a marker of cellular aging that has been linked to multiple chronic conditions.

Insomnia and risk of mortality from all-cause, cardiovascular disease, and cancer: Systematic review and meta-analysis of prospective cohort studies

Growing evidence indicates that insomnia may be associated with mortality. However, these findings have been inconsistent. We systematically searched MEDLINE and EMBASE to identify prospective cohort studies that assessed the association between insomnia disorder/individual insomnia symptoms and the risk of mortality among adults aged ≥18 yrs. We addressed this association using summary hazard ratios (HRs) and 95% confidence intervals (CIs) calculated using random-effects meta-analysis, and the GRADE approach to rate the certainty of evidence. Twenty-nine cohorts including 1,598,628 individuals (55.3% men; mean age 63.7 yrs old) with a median follow-up duration of 10.5 yrs proved eligible. Difficulty falling asleep (DFA) and non-restorative sleep (NRS) were associated with an increased risk of all-cause mortality (DFA: HR = 1.13, 95%CI 1.03 to 1.23, p = 0.009, moderate certainty; NRS: HR = 1.23, 95%CI 1.07 to 1.42, p = 0.003, high certainty) and cardiovascular disease mortality (DFA: 1.20, 95%CI: 1.01, 1.43; p = 0.04, moderate certainty; NRS: HR = 1.48, 95%CI 1.06 to 2.06, p = 0.02, moderate certainty). Convincing associations between DFA and all-cause mortality were restricted to the mid to older-aged population (moderate credibility). Insomnia disorder, difficulty maintaining sleep, and early morning awakening proved to be unassociated with all-cause and cardiovascular disease mortality. No insomnia symptoms proved to be associated with cancer-related mortality.

Influence of craniocervical and craniomandibular dysfunction to nonrestorative sleep and sleep disorders

Objective: Nonrestorative sleep and sleep disorders are commonly reported in patients suffering from craniomandibular (CMD) and craniocervical dysfunctions (CCD). This study aimed to investigate polysomnographic characteristics and the reduction of pain before and after treatment in these patients.Methods: Seventy-four patients with sleep disorders and evident CMD and CCD were included. Manual therapy and an Aqualizer® were used in the therapeutic group. Polysomnographic measurements were conducted pre- and post-therapy.Results: The number of sleep stage alterations and the sleep stage index differed significantly between pre- and post-therapeutic measurements. Between both groups, these parameters were significantly different, as well (p = .001 and p = .012). The subjective perception of sleep quality improved in 81.6% post-therapy (p < .001).Discussion: Manual therapy and the application of an Aqualizer® may improve sleep quality in patients suffering from CMD and CCD. Pain may not be the main cause for the sleep disorders in CMD and CCD.

Associations of presence or absence of exercise and/or physical activity with non-restorative sleep by gender and age: a cross-sectional study

OBJECTIVES

Non-restorative sleep (NRS) is related to qualitative aspects of sleep. The associations of NRS with exercise (EX; a planned and purposeful activity) and physical activity (PA; daily bodily movement) by gender and age have not yet been clarified. We investigated the associations of EX and/or PA with NRS by gender and age.

DESIGN

A cross-sectional study.

SETTING

The data on gender, age, presence of NRS and engagement in EX and/or PA were obtained from database and questionnaire of specified medical check-ups in FY 2013 in Japan. The analysis was conducted in 2017.

PARTICIPANTS

The subjects comprised 90 122 residents (38 603 males and 51 519 females), aged 40-74 years, who had completed the specified medical check-ups.

OUTCOME MEASURE

The presence of NRS was assessed using a question asking whether or not the subjects usually got enough sleep. NRS was considered to be present when the subjects answered 'No'. Binary logistic regression analysis was used to assess the associations of presence or absence of EX and/or PA with NRS. The OR and 95% CI of NRS prevalence were calculated and compared between those engaged in both EX and PA and the others.

RESULTS

Except for 40s and 70s among males and 40s and 50s among females, the absence of EX or PA was associated with higher ORs of NRS than referent. ORs were more than twice compared with the referents in males in their 50s (OR 2.030(95% CI 1.675 to 2.459)) and 60s (OR 2.148(95% CI 1.970 to 2.343)) and females in their 60s (OR 2.142(95% CI 1.994 to 2.302)) when they engaged in neither EX nor PA.

CONCLUSIONS

Healthcare providers must take into account the similarities and differences in the associations of EX and/or PA with NRS by gender and age when they support people with NRS.

Learning Using Concave and Convex Kernels: Applications in Predicting Quality of Sleep and Level of Fatigue in Fibromyalgia

Fibromyalgia is a medical condition characterized by widespread muscle pain and tenderness and is often accompanied by fatigue and alteration in sleep, mood, and memory. Poor sleep quality and fatigue, as prominent characteristics of fibromyalgia, have a direct impact on patient behavior and quality of life. As such, the detection of extreme cases of sleep quality and fatigue level is a prerequisite for any intervention that can improve sleep quality and reduce fatigue level for people with fibromyalgia and enhance their daytime functionality. In this study, we propose a new supervised machine learning method called Learning Using Concave and Convex Kernels (LUCCK). This method employs similarity functions whose convexity or concavity can be configured so as to determine a model for each feature separately, and then uses this information to reweight the importance of each feature proportionally during classification. The data used for this study was collected from patients with fibromyalgia and consisted of blood volume pulse (BVP), 3-axis accelerometer, temperature, and electrodermal activity (EDA), recorded by an Empatica E4 wristband over the courses of several days, as well as a self-reported survey. Experiments on this dataset demonstrate that the proposed machine learning method outperforms conventional machine learning approaches in detecting extreme cases of poor sleep and fatigue in people with fibromyalgia.

Prevalence of sleep disturbances: Sleep disordered breathing, short sleep duration, and non-restorative sleep

Recently, interest in sleep disturbances, such as sleep disordered breathing (SDB), short sleep duration, and non-restorative sleep (NRS), has been increasing. The potentially large public health implications of sleep disturbances indicate a need to determine their prevalence in a general population. This review describes the characteristics of population-based sleep cohorts from past to present. Unavoidable methodological and baseline characteristic heterogeneity was found between studies. The prevalence of SDB (apnea hypopnea index (AHI), respiratory disturbance index (RDI), or oxygen desaturation index (ODI) ≥5/h) was 24.0-83.8% in men and 9.0-76.6% in women, and that of moderate-to-severe SDB (AHI, RDI, or ODI ≥15/h) was 7.2-67.2% in men and 4.0-50.9% in women. Additionally, the prevalence of SDB in post-menopausal women was 3-6 times higher than in pre-menopausal women. The prevalence of subjective short sleep duration (<6 h) was 7.5-9.6%, while that of objective short sleep duration (<6 h) was 22.1-53.3%. The prevalence of NRS was 19.2-31.0% in men and 26.3-42.1% in women, as determined from studies using a yes-no questionnaire, while a multi-national survey using a telephone-based expert system showed a wide range of prevalence between countries, from 2.4% to 16.1%. An association between SDB, short sleep duration, and NRS has recently been suggested. To gain a better understanding of the burden of sleep disturbances, a consensus on the definition of several sleep disturbances is needed, as methodological heterogeneity exists, including SDB scoring rules, subjective versus objective data collection for short sleep duration, and the definition of NRS itself.

Nonrestorative sleep scale: reliable and valid for the Chinese population

PURPOSE

To conduct a linguistic and psychometric evaluation of a Chinese version of the Nonrestorative Sleep Scale (NRSS).

METHODS

The Chinese NRSS was created from a standard forward-backward translation and trialed on 10 Chinese adults. Telephone interviews were then conducted with 100 adults, who completed the Chinese NRSS, the Pittsburgh Sleep Quality Index (PSQI), the Athens Insomnia Scale (AIS), the Center for Epidemiological Studies Depression Scale (CES-D), and the Toronto Hospital Alertness Test (THAT). A household survey was conducted with 20 subjects, followed by a confirmatory factor analysis (CFA), and a bifactor model was developed to evaluate the reliability and validity of the NRSS.

RESULTS

The bifactor model had the root mean square error of approximation (RMSEA), standardized root mean square residual (SRMR), and comparative fit index (CFI) of 0.06, 0.06, and 0.97, respectively. Convergent validity was shown from the moderate associations with PSQI (r = - 0.66, P < 0.01), AIS (r = - 0.65, P < 0.01), CES-D (r = - 0.54, P < 0.01), and THAT (r = 0.68, P < 0.01). The coefficient omega (0.92), omega hierarchical (0.81), factor determinacy (0.93), H value (0.91), explained common variance (0.63), and percentage of uncontaminated correlations (0.80) derived from the bifactor CFA supported the essential unidimensionality of NRSS.

CONCLUSIONS

The Chinese NRSS is a valid and reliable essential unidimensional tool for the assessment of nonrestorative sleep in the Chinese population.

Sleep, chronic pain, and opioid risk for apnea

Pain is an unwelcome sleep partner. Pain tends to erode sleep quality and alter the sleep restorative process in vulnerable patients. It can contribute to next-day sleepiness and fatigue, affecting cognitive function. Chronic pain and the use of opioid medications can also complicate the management of sleep disorders such as insomnia (difficulty falling and/or staying asleep) and sleep-disordered breathing (sleep apnea). Sleep problems can be related to various types of pain, including sleep headache (hypnic headache, cluster headache, migraine) and morning headache (transient tension type secondary to sleep apnea or to sleep bruxism or tooth grinding) as well as periodic limb movements (leg and arm dysesthesia with pain). Pain and sleep management strategies should be personalized to reflect the patient's history and ongoing complaints. Understanding the pain-sleep interaction requires assessments of: i) sleep quality, ii) potential contributions to fatigue, mood, and/or wake time functioning; iii) potential concomitant sleep-disordered breathing (SDB); and more importantly; iv) opioid use, as central apnea may occur in at-risk patients. Treatments include sleep hygiene advice, cognitive behavioral therapy, physical therapy, breathing devices (continuous positive airway pressure - CPAP, or oral appliance) and medications (sleep facilitators, e.g., zolpidem; or antidepressants, e.g., trazodone, duloxetine, or neuroleptics, e.g., pregabalin). In the presence of opioid-exacerbated SDB, if the dose cannot be reduced and normal breathing restored, servo-ventilation is a promising avenue that nevertheless requires close medical supervision.

Impact of migraine on the clinical presentation of insomnia: a population-based study

BACKGROUND

Insomnia and migraine are closely related; insomnia aggravates migraine symptoms. This study was conducted to investigate the impact of migraine on the clinical presentation of insomnia symptoms.

METHODS

The data of the Korean Headache-Sleep Study (KHSS) were used in the present study. The KHSS is a nation-wide cross-sectional population-based survey regarding headache and sleep in Korean adults aged 19 to 69 years. If a participant's Insomnia Severity Index (ISI) score ≥ 10, she/he was classified as having insomnia. The clinical presentation of insomnia symptoms was assessed using total and subcomponent scores of the ISI.

RESULTS

Of 2695 participants, 290 (10.8%) and 143 (5.3%) individuals were assigned as having insomnia and migraine, respectively. The proportions of migraine (12.8% vs. 4.4%, p <  0.001) and non-migraine headache (59.0% vs. 39.9%, p <  0.001) were higher among individuals with insomnia compared to those without insomnia. Among participants with insomnia, total ISI scores were not significantly different among participants with migraine, non-migraine, and non-headache [median and interquartile range: 13.0 (11.0-17.5) vs. 13.0 (11.0-17.5) vs. 12.0 (11.0-16.0), p = 0.245]. ISI scores for noticeability of sleep problems to others were significantly higher among participants with migraine [3.0 (2.0-4.0) vs. 2.0 (2.0-3.0), p = 0.011] and non-migraine headache [3.0 (2.0-4.0) vs. 2.0 (2.0-3.0), p = 0.001] compared to those without headache history. Other ISI subcomponent scores did not significantly differ between headache status groups.

CONCLUSIONS

Participants with insomnia had an increased risk of migraine and non-migraine headache compared to those without insomnia. Among participants with insomnia, overall insomnia severity was not significantly influenced by the headache status.

A Policy Analysis of Mandatory Obstructive Sleep Apnea Screening in the Trucking Industry

Obstructive sleep apnea (OSA) is a chronic condition characterized by occlusion of the upper airway during sleep resulting in daytime sleepiness. Drivers with OSA are at a two- to sevenfold increase in risk of motor vehicle crashes (MVCs). Approximately, 13% to 28% of commercial motor vehicle drivers (CMVDs) are thought to have OSA. Obstructive sleep apnea is a significant issue in the transportation industry. Currently, The Federal Motor Carrier Safety Association (FMCSA) does not mandate OSA screening. Federal regulations only specify that CMVDs be free of "respiratory dysfunction" that would impair driving. Untreated OSA is a public safety concern. The purpose of this article is to use Bardach's eightfold policy analysis approach to examine policy options related to OSA screening in the trucking industry.

Effect of noise tolerance on non-restorative sleep: a population-based study in Hong Kong

OBJECTIVE

The aim of this study was to assess the impact of auditory noise tolerance on non-restorative sleep using an objective audiometric test in a representative sample.

DESIGN

A total of 202 Chinese individuals aged 15 years and above were recruited from a population-based household survey. Their non-restorative sleep was assessed by a single item, the degree of feeling refreshed on waking up, on a 0-10 scale, while noise tolerance was measured by the most comfortable level expressed in A-weighted decibels.

RESULTS

The 202 individuals (106 women) had a mean degree of feeling refreshed on waking up of 6.5 on the 0-10 scale and a mean maximum comfortable sound level of 69.2 dB. A multivariable analysis showed that a 1 dB increase in noise tolerance was associated with a 0.1-unit increase in the degree of feeling refreshed after adjusting for age, education, marital status, occupation, exercise, smoking, alcohol consumption, household noise level, stress, anxiety and depression. Moreover, housewives, non-smokers and individuals who were less anxious or stressed felt significantly more refreshed on waking up.

CONCLUSION

People with higher levels of noise tolerance experienced more refreshing sleep. Additional clinical consideration of enhancing noise tolerance in patients with sleep complaints is needed.

The Effect of Sleep Disorders, Sedating Medications, and Depression on Cognitive Processing Therapy Outcomes: A Fuzzy Set Qualitative Comparative Analysis

Cognitive processing therapy (CPT) for posttraumatic stress disorder (PTSD) is an effortful process requiring engagement in cognitive restructuring. Sleep disorders may lead to avoidance of effortful tasks and cognitive performance deficits. We explored whether sleep disorders, as assessed by polysomnography, were consistently associated with treatment response in combination with other factors. This study included 32 U.S. veterans who were examined both before and after CPT for combat-related PTSD. We employed a novel, case-comparative technique, fuzzy set qualitative comparative analysis (fsQCA), to identify combinations of fuzzy and crisp factors (recipes) that achieve a clinically significant outcome. Approximately one-quarter of cases experiencing clinically significant change were either (a) Vietnam era veterans without sedating medications, moderate sleep disordered breathing, and severe depression; or (b) non-Vietnam era veterans with sedating medications and without severe periodic limb movements (or significant periodic limb movement arousals). Recipes involving the absence of the relevant sleep disorder were associated with the highest coverage values. These results using fsQCA (a) provide valuable information about the heterogeneity of CPT response and (b) suggest that sleep disorders are important factors to consider in theoretical discussions of who responds to CPT for PTSD.

Insomnia identity

Insomnia identity refers to the conviction that one has insomnia, and this sleep complaint can be measured independently of sleep. Conventional wisdom predicts that sleep complaints are synchronous with poor sleep, but crossing the presence or absence of poor sleep with the presence or absence of insomnia identity reveals incongruity with expected patterns. This review of existing research on insomnia identity processes and influence finds that about one-fourth of the population are uncoupled sleepers, meaning there is an uncoupling of sleep and sleep appraisal, and daytime impairment accrues more strongly to those who endorse an insomnia identity. Research supports the conclusion that there is a cost to pathologizing sleep. Individuals claiming an insomnia identity, regardless of sleep status, are at greater risk for a range of sequelae including self-stigma, depression, suicidal ideation, anxiety, hypertension, and fatigue. A broad research agenda is proposed with hypotheses about the sources, clinical mechanisms, and clinical management of insomnia identity.

Sleep disturbances in fibromyalgia: A meta-analysis of case-control studies

OBJECTIVE

Sleep disturbances are common in fibromyalgia, but the features of sleep disturbances are not well understood. We performed a systematic review and meta-analysis of case-control studies to compare the sleep outcomes of individuals with fibromyalgia and healthy controls.

METHODS

We systematically searched eight databases (PubMed, Ovid MEDLINE, Embase, CINAHL, PsycINFO, Web of Science, Airiti Library and Wanfang Data) for articles published before April 2016.

RESULTS

Twenty-five case-controlled studies and a total of 2086 participants were included in the meta-analysis. Sleep was assessed using polysomnography and the Pittsburgh Sleep Quality Index. When sleep was assessed using polysomnography (19 studies), significant differences were observed in wake time after sleep onset (g=0.81, 95% confidence interval [CI] 0.21-1.41), total sleep time (g=-0.78, 95% CI=-1.34 to -0.15), sleep efficiency (g=-0.78, 95% CI=-1.23 to -0.32), percentage of stage 1 sleep (g=0.55, 95% CI=0.15-0.95), and percentage of slow-wave sleep (g=-0.66, 95% CI=-1.21 to -0.12) between participants with fibromyalgia and healthy controls. When sleep was assessed using the Pittsburgh Sleep Quality Index (7 studies), significant differences were observed in global scores (g=2.19, 95% CI 1.58-2.79), sleep onset latency (g=1.75, 95% CI 0.80-2.70), and sleep efficiency (g=-1.08, 95% CI -1.65 to -0.51) between participants with fibromyalgia and healthy controls.

CONCLUSION

Individuals with fibromyalgia experience lower sleep quality and sleep efficiency; longer wake time after sleep onset, short sleep duration, and light sleep when objectively assessed and more difficulty in initiating sleep when subjectively assessed. Sleep difficulties in fibromyalgia appear to be more when reported subjectively than when assessed objectively.

COMPLIANCE WITH ETHICAL STANDARDS

This study received no funding from any source. All authors declare that they have no conflict of interest. This article does not contain any studies with human participants performed by any of the authors.

Sleep Difficulties and Insomnia Symptoms in Norwegian Musicians Compared to the General Population and Workforce

Sleep problems are reported as common among performing artists and musicians. However, epidemiological research comparing musicians to different groups of the general population is lacking. For this study, 4,168 members of the Norwegian Musician's Union were invited to an online survey regarding work and health. Of the 2,121 (51%) respondents, 1,607 were active performing musicians. We measured prevalence of insomnia symptoms using the Bergen Insomnia Scale (BIS), and compared this sample to a representative sample of the general Norwegian population (n = 2,645). Overall, musicians had higher prevalence of insomnia symptoms compared to the general population (Prevalence Difference 6.9, 95% Confidence Interval 3.9-10.0). Item response analysis showed that this difference was mainly explained by nonrestorative sleep and dissatisfaction with sleep among musicians. An additional analysis, comparing musicians to the general Norwegian workforce (n = 8,518) on sleep difficulties, confirmed this tendency (Prevalence Difference 6.2, 95% Confidence Interval 4.3-8.1). Musicians performing classical, contemporary, rock, and country music reported the highest prevalence of insomnia, and these genres might be of special interest when developing preventative measures, treatment strategies, and further research on sleep difficulties among musicians.