Denise C. Jarrin

Beyond sleep duration: distinct sleep dimensions are associated with obesity in children and adolescents.

Objective:Short sleep duration is recognized as a significant risk factor in childhood obesity; however, the question as to how sleep contributes to the development of obesity remains largely unknown. The majority of pediatric studies have relied on sleep duration as the exclusive measure of sleep; this insular approach may be misleading given that sleep is a dynamic multidimensional construct beyond sleep duration, including sleep disturbances and patterns. Although these sleep dimensions partly overlap, it is necessary to determine their independent relation with obesity, which in turn, may inform a more comprehensive understanding of putative pathophysiological mechanisms linking sleep and obesity. The aim of the present study was to investigate whether sleep dimensions including sleep duration, disturbances, and patterns were individually associated with obesity, independent of multiple covariates. The second objective was to examine whether sleep disturbances and patterns were independently associated with obesity, after adjusting for sleep duration.Methods:Participants included 240 healthy children and adolescents (Mage=12.60, s.d.=1.98; 45.8% females). Anthropometric measures included measured waist and hip circumference, body mass index Z-score, and percent body fat. Subjective sleep measures included sleep duration, sleep disturbances, sleep quality, and sleep patterns from youth- and parental report.Results:Youth with larger adiposity and body composition measures reported poorer sleep quality (βavg=−0.14, P<0.01), more sleep disturbances (βavg=0.13, P<0.05), and showed a delayed sleep phase pattern (βavg=0.15, P<0.05), independent of age, sex, pubertal status, physical activity, screen time, socioeconomic status, and sleep duration. Shorter sleep duration was significantly associated with obesity; however, this link was attenuated after adjustment of covariates.Conclusions:The results suggest that sleep measures beyond duration may more precisely capture influences that drive the negative association between sleep and obesity, and thus, yield more robust associations. As such, future studies are needed to better understand how distinct sleep dimensions confer risk for childhood obesity.

The role of vulnerability in stress-related insomnia, social support and coping styles on incidence and persistence of insomnia

Individuals who are more prone to experience situational insomnia under stressful conditions may also be at greater risk to develop subsequent insomnia. While cross‐sectional data exist on the link between sleep reactivity (heightened vulnerability to stress‐related insomnia) and insomnia, limited data exist on its predictive value. The aim of the study was to evaluate prospectively whether sleep reactivity was associated with increased risk of incident and persistent insomnia in a population‐based sample of good sleepers. Social support and coping styles were also investigated as potential moderators. Participants were 1449 adults (Mage = 47.4 years, standard deviation = 15.1; 41.2% male) without insomnia at baseline and evaluated four times over 3 years. Sleep reactivity was measured using the Ford Insomnia Response to Stress Test (FIRST). Additional measures included depressive symptoms, the frequency and perceived impact of stressful life events, social support and coping styles. After controlling for prior sleep history, depressive symptoms, arousal predisposition, stressful life events and perceived impact, individuals with higher sleep reactivity had an odds ratio (OR) of 1.56 [95% confidence interval (CI): 1.13–2.16], 1.41 (95% CI: 0.87–2.30) and 2.02 (95% CI: 1.30–3.15) of developing insomnia symptoms, syndrome and persistent insomnia, respectively. Social support and coping styles did not moderate these associations. Results suggest that heightened vulnerability to insomnia is associated with an increased risk of developing new‐onset subsyndromal and persistent insomnia in good sleepers. Knowledge of premorbid differences is important to identify at‐risk individuals, as this may help to develop more targeted prevention and intervention strategies for insomnia.

Monthly fluctuations of insomnia symptoms in a population-based sample

STUDY OBJECTIVES To document the monthly changes in sleep/insomnia status over a 12-month period; to determine the optimal time intervals to reliably capture new incident cases and recurrent episodes of insomnia and the likelihood of its persistence over time. DESIGN Participants were 100 adults (mean age = 49.9 years; 66% women) randomly selected from a larger population-based sample enrolled in a longitudinal study of the natural history of insomnia. They completed 12 monthly telephone interviews assessing insomnia, use of sleep aids, stressful life events, and physical and mental health problems in the previous month. A total of 1,125 interviews of a potential 1,200 were completed. Based on data collected at each assessment, participants were classified into one of three subgroups: good sleepers, insomnia symptoms, and insomnia syndrome. RESULTS At baseline, 42 participants were classified as good sleepers, 34 met criteria for insomnia symptoms, and 24 for an insomnia syndrome. There were significant fluctuations of insomnia over time, with 66% of the participants changing sleep status at least once over the 12 monthly assessments (51.5% for good sleepers, 59.5% for insomnia syndrome, and 93.4% for insomnia symptoms). Changes of status were more frequent among individuals with insomnia symptoms at baseline (mean = 3.46, SD = 2.36) than among those initially classified as good sleepers (mean = 2.12, SD = 2.70). Among the subgroup with insomnia symptoms at baseline, 88.3% reported improved sleep (i.e., became good sleepers) at least once over the 12 monthly assessments compared to 27.7% whose sleep worsened (i.e., met criteria for an insomnia syndrome) during the same period. Among individuals classified as good sleepers at baseline, risks of developing insomnia symptoms and syndrome over the subsequent months were, respectively, 48.6% and 14.5%. Monthly assessment over an interval of 6 months was found most reliable to estimate incidence rates, while an interval of 3 months proved the most reliable for defining chronic insomnia. CONCLUSIONS Monthly assessment of insomnia and sleep patterns revealed significant variability over the course of a 12-month period. These findings highlight the importance for future epidemiological studies of conducting repeated assessment at shorter than the typical yearly interval in order to reliably capture the natural course of insomnia over time.

Measurement fidelity of heart rate variability signal processing: The devil is in the details

Heart rate variability (HRV) is a particularly valuable quantitative marker of the flexibility and balance of the autonomic nervous system. Significant advances in software programs to automatically derive HRV have led to its extensive use in psychophysiological research. However, there is a lack of systematic comparisons across software programs used to derive HRV indices. Further, researchers report meager details on important signal processing decisions making synthesis across studies challenging. The aim of the present study was to evaluate the measurement fidelity of time- and frequency-domain HRV indices derived from three predominant signal processing software programs commonly used in clinical and research settings. Triplicate ECG recordings were derived from 20 participants using identical data acquisition hardware. Among the time-domain indices, there was strong to excellent correspondence (ICC(avg)=0.93) for SDNN, SDANN, SDNNi, rMSSD, and pNN50. The frequency-domain indices yielded excellent correspondence (ICC(avg)=0.91) for LF, HF, and LF/HF ratio, except for VLF which exhibited poor correspondence (ICC(avg)=0.19). Stringent user-decisions and technical specifications for nuanced HRV processing details are essential to ensure measurement fidelity across signal processing software programs.

Objective and Subjective Socioeconomic Gradients Exist for Sleep Quality, Sleep Latency, Sleep Duration, Weekend Oversleep, and Daytime Sleepiness in Adults

Socioeconomic gradients exist for multiple health outcomes. Lower objective socioeconomic position (SEP), whether measured by income, education, or occupation, is associated with inadequate sleep. Less is known about whether ones perceived ranking of their social status, or subjective SEP, affects sleep. This study examined whether a subjective socioeconomic gradient exists for sleep while controlling for objective SEP. Participants (N = 177; age, M = 45.3 years, SD = 6.3 years) completed the Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, MacArthur Ladder, and other self-report measures to assess sleep and objective SEP. Subjective SEP trumped objective SEP as a better predictor of sleep duration, daytime sleepiness, and weekend oversleep. These findings highlight the need to expand our framework to better understand the mechanisms underlying socioeconomic gradients and sleep.

Cardiovascular autonomic dysfunction in insomnia patients with objective short sleep duration

Two phenotypes have been proposed: insomnia with objective near‐normal sleep duration, related to increased psychological symptoms, and insomnia with objective short sleep duration, associated with cardiometabolic morbidity. Reduced heart rate variability has also been implicated in the pathophysiology of cardiometabolic disease; however, there are little data on whether cardiovascular function differs between patients with objective short sleep duration and near‐normal sleep duration. Participants (Mage = 49.9 ± 11.3 years; 62.8% female) were 180 adults with chronic insomnia (Mduration = 15.7 ± 13.6). Objective sleep duration was based on total sleep time averaged across two consecutive nights of polysomnography and subjective sleep duration was based on 2‐week sleep diaries. The sample was divided into two groups, with sleep duration shorter (polysomnography‐total sleep time: n = 46; sleep diary: n = 95) or equal/longer (polysomnography‐total sleep time: n = 134; sleep diary: n = 85) than 6 hr. Electrocardiogram data derived from polysomnography were used to obtain heart rate and heart rate variability during stage 2 (N2) and rapid eye movement sleep. Heart rate variability measures included absolute and normalized high‐frequency component, an index of parasympathetic activation, and the ratio of low‐ to high‐frequency (LF/HF ratio), an index of sympathovagal balance. After controlling for covariates (e.g., co‐morbidity), patients with objective short sleep duration had reduced high‐frequency (p < .05) and elevated low‐frequency/high‐frequency ratio (p = .036) and heart rate (p = .051) compared with patients with near‐normal sleep duration. No differences were observed between phenotypes when subjective sleep duration was used. Insomnia patients with objective short sleep duration showed significantly dampened parasympathetic activation and increased sympathovagal imbalance relative to their counterparts with near‐normal sleep duration. These findings highlight the importance of treating insomnia, as treatment may reduce the risk of cardiovascular disease.

Nocturnal heart rate variability in patients treated with cognitive–behavioral therapy for insomnia.

OBJECTIVE Insomnia and reduced heart rate variability (HRV) increase the risk of cardiovascular disease and its precursors; thus, it is important to evaluate whether treatment for insomnia provides cardiovascular safeguards. The present study aimed to evaluate potential cardiovascular benefits of cognitive behavioral therapy for insomnia (CBT-I). METHOD The present study included 65 patients treated for chronic insomnia (M = 51.8 years, SD = 10.0; 66.2% female) at a university hospital. Patients received CBT-I over a 6-week period, and change scores from pre- to posttreatment derived from the Insomnia Severity Index, sleep diary, and polysomnography (PSG) were used as indices of sleep improvement. HRV variables (i.e., low frequency [LF], high frequency [HF], and the ratio of low to high frequency [LF:HF ratio]) were derived for Stage 2 (S2) and rapid-eye movement (REM) sleep at pre- and posttreatment. High HF (i.e., parasympathetic activity) and/or low LF:HF ratio (i.e., sympathovagal balance) were used as indices of HRV improvement. RESULTS Following therapy, sleep improvements, particularly for sleep onset latency, were related with reduced HF in S2 (r = .30, p < .05) and in REM (r = .36, p < .01). A trend was also observed between reduced insomnia symptoms and increased HF in REM (r = -.21, p < .10). CONCLUSIONS Findings suggest that contrary to expectations, sleep improvements following CBT-I were associated with reduced parasympathetic activation and increased sympathovagal balance. Although preliminary, these results raise the question as to whether insomnia treatment might play a role in physiological changes associated with cardiovascular anomalies. Future research is needed to examine the long-term impact of treatment as a preventative tool against insomnia-related morbidity. (PsycINFO Database Record

Insomnia and healthcare-seeking behaviors: impact of case definitions, comorbidity, sociodemographic, and cultural factors.

The public health significance of insomnia has received increased attention in the last two decades, as reflected by the numerous worldwide epidemiologic investigations documenting its prevalence, course, risk factors, and long-term outcomes. Cross-sectional studies have strengthened the evidence that insomnia is a prevalent health problem in the general population, and longitudinal studies have further documented the persistent course of insomnia and its negative outcomes on mental (e.g., depression), physical (e.g., hypertension), and occupational health (e.g., disability) [1]. The paper by Hsu et al. [2] in this issue of Sleep Medicine provides additional insight into one of several important public health aspects of insomnia, that is, healthcare-seeking behaviors. Using insurance claims of over 900,000 enrollees of the National Health Insurance program in Taiwan, the authors examined the annual rates of outpatient and inpatient consultations for insomnia from 2002 to 2009. Point prevalence estimates of healthcare-seeking behaviors varied between 2.5% and 4.2% annually, with an increasing trend over the 8-year period, whereas incidence rates fluctuated between 1.3% and 1.6% for the same interval. Significant associations were observed between increased use of healthcare services for insomnia and the female gender, those between middle and older age brackets, and the middle-class (based on socioeconomic status). These findings add to the knowledge base on healthcare-seeking behaviors. Although there were many strengths of this study, such as its use of a longitudinal design with repeated assessments, the large population-based sample, and the standard International Classification of Diseases Ninth Revision insomnia diagnostic codes, the findings must be cautiously interpreted in light of some methodologic caveats. Some of the most notable caveats were the case definition of insomnia, the lack of information regarding comorbid disorders, and the various determinants associated with healthcare-seeking behaviors.

Insomnia and hypertension: A systematic review

Insomnia is a prevalent sleep disorder that is associated with a multitude of health consequences. Particularly, insomnia has been associated with cardiovascular disease and its precursors, such as hypertension and blood pressure (BP) non-dipping. The present systematic review aimed to summarize the evidence on the concurrent and prospective associations between insomnia and hypertension and/or BP. Using electronic search engines (PubMed, SCOPUS, PsycINFO), 5,618 articles published from January 1970 to December 2017 were identified, and 64 met the inclusion criteria (26 to 162,121 participants; age range: 18-100; 46.4% male). Insomnia was based on diagnostic or non-diagnostic criteria. Hypertension was based on self-or physician-reports, antihypertensive medication use, and/or measured BP. Findings indicate that when insomnia is frequent, chronic, and/or accompanied with short sleep duration or objective markers of arousal, there is a strong association with hypertension/BP. Based on limited studies, hypertension did not significantly predict future insomnia in middle-aged adults, but did in older adults. Based on a majority of case-control studies, no differences in BP were found between participants with and without insomnia. Further research is needed to identify putative pathophysiological mechanisms underlying the link between insomnia and hypertension. The impact of insomnia therapy on BP should also be further examined in the future.

Familial Aggregation of Insomnia

Study Objectives: There is little information about familial aggregation of insomnia; however, this type of information is important to (1) improve our understanding of insomnia risk factors and (2) to design more effective treatment and prevention programs. This study aimed to investigate evidence of familial aggregation of insomnia among first‐degree relatives of probands with and without insomnia. Methods: Cases (n = 134) and controls (n = 145) enrolled in a larger epidemiological study were solicited to invite their first‐degree relatives and spouses to complete a standardized sleep/insomnia survey. In total, 371 first‐degree relatives (Mage = 51.9 years, SD = 18.0; 34.3% male) and 138 spouses (Mage = 55.5 years, SD = 12.2; 68.1% male) completed the survey assessing the nature, severity, and frequency of sleep disturbances. The dependent variable was insomnia in first‐degree relatives and spouses. Familial aggregation was claimed if the risk of insomnia was significantly higher in the exposed (relatives of cases) compared to the unexposed cohort (relatives of controls). The risk of insomnia was also compared between spouses in the exposed (spouses of cases) and unexposed cohort (spouses of controls). Results: The risk of insomnia in exposed and unexposed biological relatives was 18.6% and 10.4%, respectively, yielding a relative risk (RR) of 1.80 (p = .04) after controlling for age and sex. The risk of insomnia in exposed and unexposed spouses was 9.1% and 4.2%, respectively; however, corresponding RR of 2.13 (p = .28) did not differ significantly. Conclusions: Results demonstrate evidence of strong familial aggregation of insomnia. Additional research is warranted to further clarify and disentangle the relative contribution of genetic and environmental factors in insomnia.