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.

Short-term heart rate variability in a population-based sample of 10-year-old children.

Heart rate variability (HRV) is a non-invasive quantitative marker of cardiac autonomic function derived from continuous electrocardiogram (ECG) recordings. Normative HRV values and development factors have not been established in pediatric populations. The objective was to derive referent time- and frequency-domain HRV values for a population-based sample of children. Children aged 9-11 years (N = 1,036) participated in the Québec Longitudinal Study of Child Development cohort cardiovascular health screening. Registered nurses measured anthropometrics (height, weight) and children wore an ambulatory Holter monitor to continuously record an ECG signal. HRV variables included time (SDNN, pNN50, RMSSD, SDANN) and frequency (HF, LF, LF/HF ratio) domain variables. Normative HRV values, stratified by age, sex, and heart rate, are presented. Greater heart rate (ß avg  = -0.60, R avg (2)  = 0.39), pubertal maturation (ß avg = -0.11, R avg (2)  = 0.01), later ECG recording times (ß avg = -0.19, R avg (2)  = 0.07), and higher diastolic blood pressure (ß avg = -0.11, R avg (2)  = 0.01) were significantly associated with reduced HRV in 10-year-old children. The normative HRV values permit clinicians to monitor, describe, and establish pediatric nosologies in primary care and research settings, which may improve treatment of diseases associated with HRV in children. By better understanding existing values, the practical applicability of HRV among clinicians will be enhanced. Lastly, developmental (e.g., puberty) and procedural (e.g., recording time) factors were identified that will improve recording procedures and interpretation of results.

Autonomic dysfunction: a possible pathophysiological pathway underlying the association between sleep and obesity in children at-risk for obesity.

While mounting evidence suggests that sleep plays an important role in the etiology of obesity, the underlying pathogenic pathways are complex and unresolved. Experimental sleep deprivation studies demonstrate sympathovagal imbalance, indicative of diminished parasympathetic activity and/or heightened sympathetic activity, is consequent to poor sleep. Further, obese children exhibit sympathovagal imbalance, particularly during the night, compared to non-obese children. The question remains whether sympathovagal imbalance is one potential pathophysiological pathway underlying the association between sleep and obesity. The aim of the present study was to examine whether sympathovagal imbalance contributed to the association between sleep and obesity in children. Participants included 564 children aged 10 to 12 years (M = 11.67, SD = 0.95; 43.5% girls) from the QUALITY Cohort, a longitudinal study of children at-risk for the development of obesity. While children were at-risk due to confirmed parental obesity status, 57.7% of children were of normal body mass index (5-85th percentile). Sleep duration, sleep timing, and sleep disturbances were based on child- and parent-report. Anthropometrics were measured for central adiposity (waist circumference) and body composition (body mass index, fat mass index). Sympathovagal imbalance was derived from heart rate variability spectral analyses. Estimated path coefficients revealed that sympathovagal imbalance partially contributed to the association between poor sleep (later bedtimes, sleep-disordered breathing) and obesity. These findings highlight the importance of better understanding sympathovagal imbalance and its role in the etiology and maintenance of obesity. Future research should consider investigating nocturnal sympathovagal balance in youth.

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.

Epidemiology of Insomnia: Prevalence, Course, Risk Factors, and Public Health Burden.

This article summarizes epidemiologic evidence on insomnia, including the prevalence, incidence, and risk factors, as well as its course and consequences. Approximately 10% of the adult population suffers from an insomnia disorder and another 20% experiences occasional insomnia symptoms. Women, older adults, and people with socioeconomic hardship are more vulnerable to insomnia. Insomnia is often a chronic condition, with a 40% persistence rate over a 5-year period. Insomnia is a significant public health problem that should be addressed at the individual level with appropriate clinical care and at the population level with large-scale sleep health interventions.

The curious incident of the dog in the nighttime: The effects of pet-human co-sleeping and bedsharing on sleep dimensions of children and adolescents.

BACKGROUND: Pets are often thought to be detrimental to sleep. Up to 75% of households with children have a pet, and 30-50% of adults and children regularly share their bed with their pets. Despite these high rates, few studies have examined the effect of pet-human co-sleeping on pediatric sleep. This study compared subjective and objective sleep in youth who never, sometimes, or frequently co-slept with pets. METHODS: Children (N = 188; aged 11-17 years; M = 13.25 years) and their parents answered standardized sleep questionnaires assessing timing, duration, onset latency, awakenings, and sleep quality. Children completed a home polysomnography (PSG) sleep study for one night and wore an actigraph for two weeks accompanied with daily sleep diary. Based on reported frequency of bedsharing with pets, children were stratified into three co-sleeping groups: never (65.4%), sometimes (16.5%), frequently (18.1%). RESULTS: Overall, 34.6% of children reported co-sleeping with their pet sometimes or frequently. Results revealed largely identical sleep profiles across co-sleeping groups; findings were congruent across sleep measurement (subjective: child, parent report; objective: PSG, actigraphy). Effect sizes indicated that frequent co-sleepers had the highest overall subjective sleep quality, but longest PSG onset-latency compared to the sometimes group. CONCLUSIONS: Co-sleeping with pets was prevalent in one third of children. Sleep dimensions were similar regardless of how frequently children reported sharing their bed with their pet. Future research should examine dyadic measurement of co-sleepers to derive causal evidence to better inform sleep recommendations.

Patterns of concomitant prescription, over-the-counter and natural sleep aid use over a 12-month period: a population based study.

STUDY OBJECTIVES: Concomitant patterns of sleep aid use may provide insight for understanding the transition to chronic sleep medication use. Therefore, we sought to characterize the trajectories of concomitant natural product (NP), over-the-counter (OTC), and prescribed (Rx) sleep aid use in a population-based sample over 12-months. METHODS: Self-reported data on the use of NP, OTC, and Rx sleep aids were extracted from a Canadian longitudinal study on the natural history of insomnia (N = 3416, M age = 49.7 ± 14.7 years old; 62% women) at baseline, 6-month, and 12-month. Latent class growth modeling was used to identify latent class trajectories using MPlus Version 7. Participants completed a battery of clinical measures: Ford Insomnia Response to Stress Test, abbreviated Dysfunctional Beliefs and Attitudes about Sleep Scale, Beck Depression Inventory, Insomnia Severity Index and, the Pittsburgh Sleep Quality Index. Associations between class membership and baseline covariates were evaluated. RESULTS: Concurrent sleep aid use fell into six distinct latent class trajectories over a 12-month period: Minimal Use (74.5%), Rx-Dominant (11.3%), NP-Dominant (6.3%), OTC-Dominant (4.3%), Rx-NP-Dominant (2.4%), and Rx-OTC-Dominant (1.1%). The three latent classes with prominent prescribed agent use predicted greater incidence of healthcare professional consultations for their sleep (p < 0.05), poorer sleep quality (p < 0.001), elevated dysfunctional sleep beliefs (p < 0.001), and sleep reactivity (p < 0.001). Compared to the other four latent classes, clinical profiles of Rx-NP-dominant and Rx-OTC-dominant groups endorsed greater severity across measures. CONCLUSIONS: Patterns of sleep aid use may provide insight for identifying individuals who may be vulnerable to inappropriate self-medicating practices.

Incidence, Persistence, and Remission Rates of Insomnia Over 5 Years.

Importance: Insomnia is a significant public health problem, but there is little information on its natural history. Objective: To assess the incidence, persistence, and remission rates of insomnia over a 5-year naturalistic follow-up period. Design, Setting, and Participants: This cohort study included participants with and without sleep problems selected from the adult population in Canada from August 2007 to June 2014. Participants completed an annual survey about their sleep and health status for 5 consecutive years. Exposure: Using validated algorithms, participants were classified at each assessment as being good sleepers (n = 1717), having an insomnia disorder (n = 538), or having subsyndromal insomnia (n = 818). Main Outcomes and Measures: Survival analyses were used to derive incidence rates of new insomnia among the subgroup of good sleepers at baseline and persistence and remission rates among those with insomnia at baseline. Sleep trajectories were examined by looking at year-person transitions between each consecutive year summed over the 5-year follow-up period. All inferential analyses were weighted according to normalized sampling weights. Results: The sample included 3073 adults (mean [SD] age, 48.1 [15.0] years; range, 18.0-95.0 years; 1910 [62.2%] female). Overall, 13.9% (95% CI, 11.0%-17. 5%) of initial good sleepers developed an insomnia syndrome during the 5-year follow-up period, and incidence rates were higher among women than among men (17.6% [95% CI, 13.6%-22.7%] vs 10.1% [95% CI, 6.6%-15.3%; χ2 = 4.43; P = .03). A total of 37.5% (95% CI, 32.6%-42.5%) of participants with insomnia at baseline reported insomnia persisting at each of the 5 annual follow-up times. For subsyndromal insomnia, rates were 62.5% at 1 year to 26.5% at 5 years. For syndromal insomnia, rates were 86.0% at 1 year to 59.1% at 5 years. Conversely, remission rates among those with subsyndromal insomnia were almost double the rates among those with an insomnia syndrome at 1 year (37.5% [95% CI, 31.7%-44.0%] vs 14.0% [95% CI, 9.3%-20.8%]), 3 years (62.7% [95% CI, 56.7%-68.7%] vs 27.6% [95% CI, 20.9%-35.9%]), and 5 years (73.6% [95% CI, 68.0%-78.9%%] vs 40.9% [95% CI, 32.7%-50.4%]). Yearly trajectories showed that individuals who were good sleepers at baseline were 4.2 (95% CI, 3.51-4.89) times more likely to stay good sleepers in the subsequent year, but once they developed insomnia, they were equally likely to report symptoms (47% probability) than to return to a good sleeper status (53% probability) 1 year later. Similarly, those with an insomnia syndrome at any given assessment were more likely (adjusted odds ratio, 1.60; 95% CI, 1.19-2.60) to remain in that status (persistence) than to improve (remittance) at the next assessment; even among those who improved, the odds of relapse were greater (adjusted odds ratio, 2.04; 95% CI, 1.23-3.37) than those to improve in the following year. Conclusions and Relevance: The findings suggest that insomnia is often a persistent condition. Considering the long-term adverse outcomes associated with persistent insomnia, these findings may have important implication for the prognosis and management of insomnia.

Parental Expectations Are Associated with Children's Sleep Duration and Sleep Hygiene Habits.

OBJECTIVE: Although parents recognize the importance of sleep, most have a limited understanding of children's sleep needs. This study examined whether parental expectations about sleep were linked to children and adolescent's sleep duration and sleep hygiene. METHOD: Participants included 376 unique parent-child dyads. Parents (mean age = 47.0 years, SD = 6.7) estimated the number of hours of sleep their children (mean age = 13.0 years, SD = 2.2; 9-17 years) needed. These estimates were age-matched with recommended pediatric guidelines of the American Academy of Sleep Medicine and the National Sleep Foundation to yield 3 groups: expect less (8%-11%), expect appropriate (85%-89%), and expect more (3%-4%). Sleep duration for school nights and weekends were reported by children and parents. Sleep hygiene included sleep-promoting practices (quiet, dark bedroom, regular bed/wake times, consistent routine) and sleep-interfering practices (physiological arousal, presleep worry, alcohol/smoking intake, daytime napping, screen time). RESULTS: Most parents (68.7%) endorsed that children do not get enough sleep. Linear and logistic regressions were used to assess the impact of parental expectations. For every additional hour of sleep expected, children slept between 15.5 (parent-report 95% confidence interval [CI], 9.0-22.0) and 17.9 minutes (child-report 95% CI, 9.7-26.2) longer on school nights, adjusted for age, sex, puberty, and parental education. For parents who expected less sleep than recommended, their children had the shortest sleep duration, least favorable sleeping environments, and greater presleep worry. CONCLUSION: Parental sleep expectations were directly linked to children's sleep duration. Pediatricians and primary care providers can mobilize knowledge to optimally convey accurate information about developmental sleep needs and recommended hours to parents to promote longer sleep.

Insomnia treatment response as a function of objectively measured sleep duration.

OBJECTIVES: To examine the potential moderating effect of objectively measured sleep duration at baseline on the response to cognitive behavioral therapy for insomnia (CBT-I), administered singly or combined with medication (CBT-I + Med). METHODS: Based on the average PSG-derived sleep duration across two baseline nights and the type of treatment received, 159 adults with insomnia (50.3 ± 10.1 years; 61.0% women) were classified into one of four groups: participants with short sleep duration (ie, ≤ 6 h) treated with CBT-I (n = 26) or CBT-I+Med (n = 25), and participants with normal sleep duration (ie, > 6 h) treated with CBT-I (n = 54) or CBT-I+Med (n = 54). Primary outcome measures were sleep/wake parameters derived from a sleep diary and insomnia severity and secondary outcomes were beliefs about sleep, fatigue, depression and anxiety. RESULTS: Patients with both short and normal sleep durations at baseline improved significantly on most sleep continuity parameters with CBT-I administered singly or combined with medication. Irrespective of treatment received, participants with short sleep duration also showed significantly greater improvements in subjective sleep (ie, reduced wake after sleep onset, increased sleep efficiency) relative to those with normal sleep duration. Conversely, participants with normal sleep duration showed greater improvements on some measures of daytime functioning and sleep satisfaction. CONCLUSIONS: There was no moderating effect of baseline sleep duration on treatment response to cognitive behavioral therapy. Despite some marginal differential treatment response on selected daytime functioning outcomes, the benefits from CBT-I were not significantly different as a function of short or normal sleep duration at baseline. Further prospective investigation of insomnia phenotypes taking into account other variables than sleep duration is warranted in order to develop more targeted insomnia therapies. TRIAL REGISTRATION: www.clinicaltrials.gov (#NCT00042146).

A systematic review of cognitive behavioral therapy for insomnia implemented in primary care and community settings.

The advent of stepped-care and the need to disseminate cognitive behavioral therapy for insomnia (CBT-I) has led to novel interventions, which capitalize on non-specialist venues and/or health personnel. However, the translatability of these CBT-I programs into practice is unknown. This review evaluates the current state of CBT-I programs that are directly implemented in primary care and/or community settings. A literature search was conducted through major electronic databases (N = 840) and through snowballing (n = 8). After removing duplicates, 104 full-texts were extracted and evaluated against our initial inclusion criteria. Twelve studies including data from 1625 participants were subsequently evaluated for its study design and methodological quality. CBT-I program components varied across studies and included cognitive therapy (n = 6), relaxation (n = 7), sleep restriction therapy (n = 9), stimulus control therapy (n = 11) and sleep psychoeducation (n = 12). The respective interventions produced small to moderate post-treatment weighted effect sizes for the Insomnia Severity Index (0.40), Pittsburgh Sleep Quality Index (0.37), sleep efficiency (0.38), sleep onset latency (0.38), and wake time after sleep onset (0.46) but total sleep time (0.10) did not reach statistical significance. While non-specialist community settings can potentially address the demands for CBT-I across clinical contexts, intervention heterogeneity precluded the full impact of the 12 CBT-I programs to be evaluated.

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.

Investigating psychological and physiological responses to the Trier Social Stress Test in young adults with insomnia.

OBJECTIVE: Stress and hyperarousal both contribute to insomnia. Elevated stress-related sleep reactivity is associated with hyperarousal, and might constitute a vulnerability to future insomnia. The present study examined acute stress-induced arousal and its association with nocturnal sleep. METHODS: Participants were 30 healthy adults (66.7% female, Mage = 26.7 years): 10 with insomnia (INS) and 20 good sleepers with high vulnerability (HV) or low vulnerability (LV) to insomnia. They underwent two consecutive nights of polysomnography. During the evening preceding the second night, the Trier Social Stress Test (TSST) was administered, and psychological and physiological arousal indices were assessed. RESULTS: The TSST elicited an increase in psychological and physiological arousal in all three groups. The INS group showed greater acute cortisol response (p < 0.05) and secretion at bedtime (p < 0.05), and higher pre-sleep cognitive arousal (p < 0.01) than the LV group; HV participants did not significantly differ from those in the INS or the LV group. Increased cortisol response and elevated sympathovagal imbalance (ie, low frequency/high frequency ratio) were each significantly associated with longer nocturnal awakenings (p = 0.048, p = 0.037, respectively). Heightened blood pressure was significantly associated with prolonged sleep onset latency, and reduced total sleep time and sleep efficiency (all ps < 0.05). CONCLUSIONS: These findings support the hyperarousal conceptualization of insomnia and indirectly suggest that increased stress reactivity and bedtime hyperarousal might represent a trait-like vulnerability in certain good sleepers. More research is warranted to validate and expand these preliminary findings.

Qualitative studies of insomnia: Current state of knowledge in the field.

Despite its high prevalence and burden, insomnia is often trivialized, under-diagnosed, and under-treated in practice. Little information is available on the subjective experience and perceived consequences of insomnia, help-seeking behaviors, and treatment preferences. The use of qualitative approaches (e.g., ethnography, phenomenology, grounded theory) may help gain a better understanding of this sleep disorder. The present paper summarizes the evidence derived from insomnia studies using a qualitative research methodology (e.g., focus group, semi-structured interviews). A systematic review of the literature was conducted using PsycINFO and Medline databases. The review yielded 22 studies and the quality of the methodology of each of them was evaluated systematically using the critical appraisal skills programme (CASP) appraisal tool. Selected articles possess at least a very good methodological rigor and they were categorized according to their main focus: "Experience of insomnia", "Management of insomnia" and "Medicalization of insomnia". The main findings indicate that: 1) insomnia is often experienced as a 24-h problem and is perceived to affect several domains of life, 2) a sense of frustration and misunderstanding is very common among insomnia patients, which is possibly due to a mismatch between patients' and health care professionals' perspectives on insomnia and its treatment, 3) health care professionals pay more attention to sleep hygiene education and medication therapies and less to the patient's subjective experience of insomnia, and 4) health care professionals are often unaware of non-pharmacological interventions other than sleep hygiene education. An important implication of these findings is the need to develop new clinical measures with a broader scope on insomnia and more targeted treatments that take into account the patient's experience of insomnia. Greater use of qualitative approaches in future research may produce novel and more contextualized information leading to a more comprehensive understanding of insomnia.

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.

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

Temporal Stability of the Ford Insomnia Response to Stress Test (FIRST).

STUDY OBJECTIVES: The Ford Insomnia Response to Stress Test (FIRST) is a self-report tool that measures sleep reactivity (i.e., vulnerability to experience situational insomnia under stressful conditions). Sleep reactivity has been termed a "trait-like" vulnerability; however, evidence of its long-term stability is lacking. The main objective of the current psychometric study was to investigate the temporal stability of the FIRST over two 6-mo intervals in a population-based sample of adults with and without insomnia. The temporal stability of the FIRST was also compared with the temporal stability of other scales associated with insomnia (trait-anxiety, arousability). METHODS: Participants included 1,122 adults (mean age = 49.9 y, standard deviation = 14.8; 38.8% male) presenting with an insomnia syndrome (n = 159), insomnia symptoms (n = 152), or good sleep (n = 811). Participants completed the FIRST, the State-Trait Anxiety Inventory (trait-anxiety), and the Arousal Predisposition Scale (arousability) on three different occasions: baseline and at 6- and 12-mo follow-up. Intraclass correlation coefficients (ICCs) were computed for all scales (baseline to 6 mo and 6 to 12 mo). RESULTS: The FIRST yielded strong temporal stability from baseline to 6 mo among those with insomnia syndrome (ICC = 0.81), symptoms (ICC = 0.78), and good sleep (ICC = 0.81). Similar results were observed for 6 to 12 mo among those with insomnia syndrome (ICC = 0.74), insomnia symptoms (ICC = 0.82), and good sleep (ICC = 0.84). The stability of the FIRST was not comparable with the stability of trait-anxiety, but was somewhat comparable with the stability of arousability. CONCLUSIONS: Overall, the FIRST is a temporally reliable stable scale over 6-mo intervals. Future research is needed to corroborate the stability and trait-like measures of sleep reactivity with physiological, behavioural and personality measures.

Objective and subjective socioeconomic gradients exist for sleep in children and adolescents.

OBJECTIVE: Socioeconomic position (SEP) is inversely associated with many health outcomes, yielding a socioeconomic gradient in health. In adults, low SEP is associated with short sleep duration, poorer sleep quality, and difficulty initiating and maintaining sleep. Relatively little is known about this relation in youth. The aim of the present study was to examine whether socioeconomic gradients exist for various sleep indices among a healthy sample of children and adolescents. METHOD: Participants took part in the larger Healthy Heart Project and included 239 youth (69.6% Caucasian; 45.6% female), aged 8-17 years (M = 12.6, SD = 1.9). Parental income and education were used to measure objective SEP. The Subjective Social Status Scale-Youth Version was used to measure subjective SEP. Sleep duration, sleep quality, daytime sleepiness, and sleep disturbances were assessed through self- and parent-report. RESULTS: In children, objective SEP was related with sleep duration (ß = .35, p < .01), although subjective SEP was related with daytime sleepiness (ßavg = .33, p < .01) and parent-reported sleep duration (ß = .23, p < .05). In adolescents, subjective SEP was related with sleep quality (ß = .28, p < .01) and parent-reported sleep duration (ß = -.18, p < .05), even after controlling for objective SEP. CONCLUSIONS: Socioeconomic gradients were observed for multiple sleep measures in youth. Objective parental SEP was related with sleep complaints (e.g., sleep disturbances), and subjective SEP was related with sleep quality and daytime sleepiness. Findings suggest sleep may be one pathway underlying the socioeconomic gradient in health. Future research should aim to elucidate how distinct sleep constructs may explain how socioeconomic status "gets under the skin" to affect health.

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.