Association of job strain with accelerometer-based sleep duration and timing of sleep among older employees.

Job strain has been associated with poor sleep quality and could lead to changes in duration and timing of sleep as well. This study examined the association of job strain with sleep duration, bedtimes and awakening times among public sector employees close to their retirement age. Differences in these sleep parameters between workdays and free days across job strain groups were examined. Duration and timing of sleep were measured repeatedly with accelerometers among 466 public sector employees in Finland (mean age 63 years, 86% women), who contributed to 759 measurements in total. Job demands (low/high) and control (low/high) measured by self-reports and job exposure matrix were used to identify low strain (low demand, high control), passive (low, low), active (high, high) and high strain (high, low) jobs. No differences in sleep duration were observed on workdays, whereas on free days those in the high strain group had longer sleep duration than those in the low strain and passive job groups. The high strain group also extended their sleep from workdays to free days more, the extension being on average 59 min (95% CI 42 min-75 min) when adjusted for several sociodemographic, work and health factors. This extension of sleep duration resulted mostly from a greater delay of awakening times from workdays to free days. Psychosocial work factors, such as job strain, need to be considered when promoting sufficient sleep duration among older employees, as those with job strain may have a greater need for recovery and sleep.

Work participation trajectories among 1,098,748 Finns: reasons for premature labour market exit and the incidence of sickness absence due to mental disorders and musculoskeletal diseases.

BACKGROUND: Early exit from paid employment is a notable public health and societal challenge. Previous research has largely focused on the relationships among variables instead of the relationships among individuals with different work participation history. Person-oriented methods enable to identify latent groups of individuals who are likely to follow similar development in their work participation over time. We thus aimed to identify work participation trajectories during early and midlife careers and their social determinants using large nationally representative data comprising over 1 million initially employed individuals and a 10-year follow-up for their work participation. A further aim was to determine the cumulative incidence of sickness absence due to key diagnostic groups, mental disorders and musculoskeletal diseases within the trajectories. METHODS: Young (25-38 years at baseline, n = 495,663) and midlife (39-52 years at baseline, n = 603,085) Finnish people, all working in 2004, were followed up through 2013, with registers of the Social Insurance Institution, and the Statistics Finland. The registers provided data for work participation and its determinants, as well as for computing the cumulative incidence of sickness absence. Latent class growth analysis was used to identify trajectories. RESULTS: Three distinctive trajectories were identified: temporary exit, permanent exit, and continuously employed people. As compared to the other trajectories, those belonging to the permanent exit trajectory were more likely men, manual workers and had a lower income. The cumulative incidence of sickness absence due to mental disorders was highest in the permanent exit trajectory group. For musculoskeletal diseases, the cumulative incidence of sickness absence increased in the permanent exit trajectory mainly in the older age groups. CONCLUSION: Distinct group-based trajectories of early work exit can be identified in a representative cohort of initially employed people. Focusing on the determinants of premature exit and early intervention to tackle increasing sickness absence may promote work participation particularly in the most vulnerable groups.

Prevalence of insomnia-related symptoms continues to increase in the Finnish working-age population.

In 2008, we published epidemiological data from 1972 to 2005 that suggested an increase in insomnia-related symptoms among the working-age population. The results were based on the National FINRISK (FR) Study samples of the Finnish adult population aged 25-64, and on the Finnish Quality of Work Life Surveys (FQWLS), carried out among Finnish salary earners. Both of these ongoing studies have since provided two new estimates of insomnia-related symptoms. Chronic insomnia-related symptoms were 9.0% (95% CI 8.3-9.7), 9.6% (95% CI 8.8-10.4) in FR 2007 and 2012, respectively; and 9.1% (95% CI 8.3-10.0), 9.2% (95% CI 8.4-10.1) in FQWLS 2008 and 2013, respectively. Occasional insomnia-related symptoms were 45.3% (95% CI 44.1-46.6), 42.5% (95% CI 41.1-43.9) in FR 2007 and 2012, respectively; and 40.3% (95% CI 38.8-41.7), 44.8% (95% CI 41.1-43.9) in FQWLS 2008 and 2013, respectively. The new estimates further strengthen the interpretation of the ongoing increase in occasional insomnia-related symptoms among the Finnish general adult population. The increase in occasional symptoms was most prominent among employees. However, chronic insomnia symptoms showed no further increase.

Winter is coming: nightmares and sleep problems during seasonal affective disorder.

Sleep problems, especially nightmares and insomnia, often accompany depression. This study investigated how nightmares, symptoms of insomnia, chronotype and sleep duration associate with seasonal affective disorder, a special form of depression. Additionally, it was noted how latitude, a proxy for photoperiod, and characteristics of the place of residence affect the prevalence of seasonal affective disorder and sleep problems. To study these questions, data from FINRISK 2012 study were used. FINRISK 2012 consists of a random population sample of Finnish adults aged 25-74 years (n = 4905) collected during winter from Finnish urban and rural areas spanning the latitudes of 60°N to 66°N. The Seasonal Pattern Assessment Questionnaire was used to assess symptoms of seasonal affective disorder. Participants with symptoms of seasonal affective disorder had significantly increased odds of experiencing frequent nightmares and symptoms of insomnia, and they were more often evening chronotypes. Associations between latitude, population size and urbanicity with seasonal affective disorder symptoms and sleep disturbances were generally not significant, although participants living in areas bordering urban centres had less sleep problems than participants from other regions. These data show that the prevalence of seasonal affective disorder was not affected by latitude.

Self-reported obstructive sleep apnea, simple snoring, and various markers of sleep-disordered breathing as predictors of cardiovascular risk.

PURPOSE: Our objective was to investigate whether self-reported obstructive sleep apnea (OSA), simple snoring, and various markers of sleep-disordered breathing (SDB) are associated with cardiovascular risk. METHODS: We examined a representative nationwide cohort of 5177 Finnish adults aged ≥30 years. The participants underwent measurement of traditional cardiovascular risk factors and answered SDB-related questions derived from the Basic Nordic Sleep Questionnaire, which were used to operationalize self-reported OSA. The primary end point was incidence of a cardiovascular event (cardiovascular mortality, non-fatal myocardial infarction, non-fatal stroke, hospitalization for heart failure, or coronary interventions). RESULTS: During a median follow-up of 11.2 years and 52,910 person-years of follow-up, 634 participants suffered a cardiovascular event. In multivariable-adjusted Cox models, self-reported OSA (hazard ratio [HR] 1.34; 95 % confidence interval [CI] 1.04-1.73; p = 0.03) was an independent predictor of cardiovascular events. Self-reported simple snoring by itself was not associated with future cardiovascular events (HR 0.88 versus non-snorers, 95 % CI 0.75-1.04, p = 0.15). However, among snorers (n = 3152), frequent breathing cessations (HR 2.19, 95 % CI 1.26-3.81, p = 0.006) and very loud and irregular snoring (HR 1.82, 95 % CI 1.31-2.54, p < 0.001) were associated with cardiovascular risk. CONCLUSIONS: Self-reported OSA and SDB-related snoring variables are associated with cardiovascular risk, whereas simple snoring is not. In clinical practice and in surveys, questions concerning only habitual snoring should be amended with questions focusing on respiratory pauses and snoring stertorousness, which can be used to estimate the risk of OSA and cardiovascular events.

Trends in self-reported sleep problems, tiredness and related school performance among Finnish adolescents from 1984 to 2011.

The aim of this study was to investigate long-term trends in insomnia symptoms, tiredness and school performance among Finnish adolescents. A time-series from 1984 to 2011 was analysed from two large-scale survey studies, the Finnish School Health Promotion Study and the Health Behavior in School-Aged Children study. A total of 1,136,583 adolescents aged 11-18 years answered a standardized questionnaire assessing frequency of insomnia symptoms, tiredness and school performance. A clear approximately twofold increasing trend in insomnia symptoms and tiredness was found from the mid-1990s to the end of the 2000s. The increase was evident in all participating age groups and in both genders. After 2008, the increase seems to have stopped. Insomnia symptoms and tiredness were associated with lower school performance and they were more prevalent among girls (11.9 and 18.4%) compared to boys (6.9 and 9.0%, respectively). Unexpectedly, we also observed an increasingly widening gap in school performance between normally vigilant and chronically tired pupils. The underlying causes of these phenomena are unknown, but may concern changes in the broader society. The observed recent increasing trend in adolescents' sleep problems is worrisome: poor sleep quality has also been suggested to associate with clinical or subclinical mood or anxiety disorders and behavioural problems and predispose to sleep and psychiatric disorders later in life. Our results justify further studies and call for serious attention to be paid to adolescent's sleep in the Finnish educational system and society at large.

Interrelationships of Physical Activity and Sleep with Cardiovascular Risk Factors: a Person-Oriented Approach.

PURPOSE: Associations of behaviorally modifiable factors like physical activity (PA), sedentary behaviors, and sleep with cardiovascular diseases (CVDs) are complicated. We examined whether membership in latent classes (LCs) differentiated by PA and sleep profiles (real-life clustering of behaviors in population subgroups) associate with metabolic risk factors and CVD risk. METHODS: The National FINRISK 2012 Study comprise a cross-sectional sample of 10,000 Finns aged 25 to 74 years. Analyses included participants with complete data on a health questionnaire, a health examination, who had no prevalent CVD (n = 4031). LCs with PA and sleep profiles were previously defined using latent class analysis. Ten metabolic risk factors and the Framingham 10-year CVD risk score were compared between the LCs. RESULTS: PA and sleep class profiles were substantially similar for genders. Compared to LC-1, with a profile including high PA and sufficient sleep, membership in LC-4, with a profile including sedentariness and insufficient sleep was associated with high metabolic risk factors in women but not in men. In women, also membership in LC-2, with a profile including light PA, sufficient sleep, and high sedentariness was associated with high metabolic risk factors. The Framingham 10-year CVD risk score was highest in LCs 2 and 4 in both genders. CONCLUSIONS: Membership in LCs differentiated by PA and sleep profiles was associated with metabolic risk factors merely in women, suggesting gender differences in the interrelationships of health behaviors and metabolic risk factors. Total CVD risk differed between the LCs despite of gender; however, the effect was small.

Genome-wide association study of sleep duration in the Finnish population.

Sleep duration is genetically regulated, but the genetic variants are largely unknown. We aimed to identify such genes using a genome-wide association study (GWAS) combined with RNA expression at the population level, and with experimental verification. A GWAS was performed in a Finnish sample (n = 1941), and variants with suggestive association (P < 5 × 10(-5) ) were tested in a follow-up sample from the same population with sleep duration (n = 6834) and time in bed (n = 1720). Variants with pointwise association of P < 0.05 in the follow-up sample were analysed further. First, we correlated genotypes with transcript expression levels with sleep duration (n = 207). The expression levels of significant transcripts were further studied in experimental sleep restriction. Of the 31 variants with P < 5 × 10(-5) in the discovery sample, three variants showed nominal allelic association (P < 0.05) in the follow-up sample: rs10914351, near PTPRU (P = 0.049), rs1037079 in PCDH7-CENTD1 (P = 0.011) and rs2031573 near KLF6 (P = 0.044). The risk alleles for shorter sleep (rs2031573 and rs1037079) were also associated with higher KLF6 and PCDH7 expression levels (P < 0.05). Experimental sleep restriction increased the expression of KLF6 (P < 0.01). These data suggest that rs2031573 near KLF6 or related loci and rs1037079 between PCDH7-CENTD1 or related loci may contribute to the regulation of sleep duration via gene expression. These results illustrate the utility of combining different analytical approaches to identify genetic determinants for traits related to sleep physiology. However, additional studies are needed in order to understand the roles of KLF6 and PCDH7 in sleep regulation.

Physical activity and sleep profiles in Finnish men and women.

BACKGROUND: Physical activity (PA) and sleep are related to cardiovascular diseases (CVD) and their risk factors. The interrelationship between these behaviors has been studied, but there remain questions regarding the association of different types of PA, such as occupational, commuting, and leisure time to sleep, including quality, duration and sufficiency. It is also unclear to what extent sleep affects peoples' PA levels and patterns. Our aim is to investigate the interrelationship between PA and sleep behaviors in the Finnish population, including employment status and gender. METHODS: The study comprised population based data from the FINRISK 2012 Study. A stratified, random sample of 10,000 Finns, 25 to 74 years-old, were sent a questionnaire and an invitation to a health examination. The participation rate was 64% (n = 6,414). Latent class analysis was used to search for different underlying profiles of PA and sleep behavior in men and women, respectively. Models with one through five latent profiles were fitted to the data. Based on fit indicators, a four-class model for men and women, respectively, was decided to be the best fitted model. RESULTS: Four different profiles of PA and sleep were found in both men and women. The most common profile of men comprised 45% of the total participants, and in women, 47%. These profiles were distinguished by probabilities for high leisure time PA and sleep, subjectively rated as sufficient, as well as sleep duration of 7-7.9 hours. The least common profiles represented 5% (men) and 11% (women) of the population, and were characterized by probabilities for physical inactivity, short sleep, and evening type for women and morning type for men. There was also one profile in both genders characterized by likelihood for both high occupational PA and subjectively experienced insufficient sleep. CONCLUSIONS: The use of latent class analysis in investigating the interrelationship between PA and sleep is a novel perspective. The method provides information on the clustering of behaviors in people and the profiles found suggest an accumulative nature of leisure time PA, and better sleep. Our data also suggest that high levels of occupational PA are associated with shorter and poorer sleep.

Sociodemographic and socioeconomic differences in sleep duration and insomnia-related symptoms in Finnish adults.

BACKGROUND: Poor sleep tends to be patterned by sociodemographic and socioeconomic factors. The aim of this study was to examine the associations of sociodemographic and socioeconomic factors with sleep duration and insomnia-related symptoms across life course. METHODS: We used cross-sectional Health 2000 Survey (2000-2001) among a total of 5,578 adult Finns, aged 30-79 years, representative of adult Finnish population. Data about sociodemographic and socioeconomic circumstances, insomnia-related symptoms over the previous month as well as average sleep duration were collected by questionnaires. Multinomial logistic regression models were adjusted first for gender and age, second for sociodemographic factors, third additionally for socioeconomic factors, and fourth for all covariates and self-perceived health simultaneously. RESULTS: On average 70% of Finnish adults slept 7-8 hours a day. Frequent insomnia-related symptoms were more prevalent among women (14%) than men (10%). Not being married, not having children, having low education, low income, being unemployed, and being a disability retiree were associated with frequent insomnia-related symptoms. Similar factors were associated with short and long sleep duration. However, childhood socioeconomic position was mostly unrelated to sleep in adulthood except parental education had some associations with short sleep duration. CONCLUSIONS: Disadvantaged socioeconomic position in adulthood, in particular income and employment status, is associated with poorer sleep. When promoting optimal sleep duration and better sleep quality, families with low incomes, unemployed people, and disability retirees should be targeted.

Psychomotor slowness is associated with self-reported sleep duration among the general population.

Short and long self-reported sleep durations have been found to be associated with several seemingly disparate health risks and impaired functional abilities, including cognitive functioning. The role of long sleep is especially poorly understood in this context. Psychomotor slowness, shown to have analogous associations with cognitive performance and health risks as self-reported long sleep duration, has not been studied together with sleep duration in epidemiological settings. We hypothesized that self-reported habitual sleep duration, especially long sleep, is associated with slow psychomotor reaction time, and that this association is independent of vigilance-related factors. The hypothesis was tested in a sample of 5352 individuals, representing the general adult population. We found a U-shaped association between self-reported sleep duration and psychomotor speed, which prevailed even after controlling for several pertinent confounders. This novel finding can be interpreted to mean that self-reported sleep duration, at least in the case of long sleep, is an indicator of bodily/brain integrity and, taken together with the results of cognitive epidemiology, may provide some new insights into the mechanisms underlying the associations between habitual self-reported sleep duration, health risks and impaired functional abilities.

Associations of Sleep and Health Functioning with Premature Exit from Work: A Cohort Study with a Methodological Emphasis.

Sleep and functioning are associated with a risk of early workforce exit. However, patterns of change in sleep and functioning through time have not been investigated using person-oriented approaches to show what features of sleep and functioning are associated with an early exit. We examined the pattern of interactions between sleep and health functioning characterizing homogenous subgroups of employees and their associations with premature work exit. An additional aim was to provide a tutorial providing detailed description on how to apply these models, compared to traditional variable based risk factors. We analyzed data from 5148 midlife employees of the City of Helsinki, Finland, surveyed over three phases (2000-02, 2007, and 2012). Using repeated measures latent class analyses (RMLCA) we classified people into groups based on their trajectories in sleep and functioning. We identified four longitudinal groups: (1) Stable good sleep and functioning (reference), (2) Persistent sleep problems and good or moderate functioning, (3) Poor functioning with good sleep, and (4) Problematic sleep and health functioning. Compared to group 1, elevated risk was found in all classes with group 4 being the worst. In conclusion, focusing on person-orientated patterns of interactions between sleep and functioning helped produce qualitatively different and quantitatively stronger predictions than using conventional risk factor methodology. Thus, longitudinal person-oriented approaches may be a more powerful method for quantifying the role of sleep and health functioning as risks for premature exit from work.

A population-based association study of candidate genes for depression and sleep disturbance.

The clinical manifestation of depression comprises a variety of symptoms, including early morning awakenings and fatigue, features also indicating disturbed sleep. The presence or absence of these symptoms may reflect differences in neurobiological processes leading to prolonged depression. Several neurobiological mechanisms have been indicated in the induction of depression, including disturbances in serotonergic and glutamatergic neurotransmission and in the action of the hypothalamic-pituitary-adrenal (HPA) axis. The same transmitters have also been linked to sleep regulation. We hypothesized that depression without simultaneous symptoms of disturbed sleep would partly have a different genetic background than depression with symptoms of disturbed sleep. We tested this hypothesis using a systematic population-based association study of 14 candidate genes related to depression and disturbed sleep. Association of genetic variants with either depression alone, depression with early morning awakenings, or depression with fatigue was investigated using permutation-based allelic association analysis of a sample of 1,654 adults recruited from Finland's population-based program. The major findings were associations of TPH2 (rs12229394) with depression accompanied by fatigue in women and CREB1 (rs11904814) with depression alone in men. We also found suggestive associations in women for GAD1, GRIA3, and BDNF with depression accompanied by fatigue, and for CRHR1 with depression accompanied by early morning awakenings. The results indicate sex-dependent and symptom-specific differences in the genetic background of depression. These differences may partially explain the broad spectrum of depressive symptoms, and their systematic monitoring could potentially be used for diagnostic purposes.

Changes in accelerometer-measured sleep during the transition to retirement: the Finnish Retirement and Aging (FIREA) study.

STUDY OBJECTIVES: Retirement is associated with increases in self-reported sleep duration and reductions in sleep difficulties, but these findings need to be confirmed by using more objective measurement tools. This study aimed at examining accelerometer-based sleep before and after retirement and at identifying trajectories of sleep duration around retirement. METHODS: The study population consisted of 420 participants of the Finnish Retirement and Aging study. Participants' sleep timing, sleep duration, time in bed, and sleep efficiency were measured annually using a wrist-worn triaxial ActiGraph accelerometer on average 3.4 times around retirement. In the analyses, sleep on nights before working days and on nights before days off prior to retirement were separately examined in relation to nights after retirement. RESULTS: Both in bed and out bed times were delayed after retirement compared with nights before working days. Sleep duration increased on average by 41 min (95% confidence interval [CI] = 35 to 46 min) from nights before working days and decreased by 13 min (95% CI = -20 to -6 min) from nights before days off compared with nights after retirement. By using latent trajectory analysis, three trajectories of sleep duration around retirement were identified: (1) shorter mid-range sleep duration with increase at retirement, (2) longer mid-range sleep duration with increase at retirement, and (3) constantly short sleep duration. CONCLUSIONS: Accelerometer measurements support previous findings of increased sleep duration after retirement. After retirement, especially out bed times are delayed, thus, closely resembling sleep on pre-retirement nights before non-working days.

Self-reported sleep duration and cognitive functioning in the general population.

This study investigated the relationship between self-reported sleep factors (sleep duration, insomnia, use of sleeping medicine, probable sleep apnoea and feelings of fatigue and tiredness) with cognitive functioning in 5177 people aged 30 years or older from a cross-sectional representative sample of the adult population in Finland (The Finnish Health 2000 Survey). Previous studies have indicated a U-shaped association between increased health risks and sleep duration; we hypothesized a U-shaped association between sleep duration and cognitive functioning. Objective cognitive functioning was assessed with tasks derived from the Consortium to Establish a Registry for Alzheimer's Disease test battery (verbal fluency, encoding and retaining verbal material). Subjective cognitive functioning and sleep-related factors were assessed with questionnaires. Health status was assessed during a health interview. Depressive and alcohol use disorders were assessed with the Composite International Diagnostic Interview. Medication was recorded during the health examination. Short and long sleep duration, tiredness and fatigue were found to be associated with both objectively assessed and self-reported decreased cognitive functioning. The association was stronger between sleep factors and subjective cognitive function than with objective cognitive tests. These data suggest that self-reported habitual short and long sleep duration reflect both realization of homeostatic sleep need and symptom formation in the context of the individual's health status.

Trajectories in hypnotic use and approaching death: a register linked case-control study.

PURPOSE: Whether the association between hypnotic and increased mortality risk is created by causation or confounding, has been long debated. We further examined the possibility of confounding by indication with a comprehensive approach. METHODS: The National FINRISK Study cohorts of 1997, 2002, and 2007 (25,436 participants aged 25-74) were followed up until July 2012. There were 1822 deaths, and at least one gender, baseline age and cohort matched 'control' was found for 1728 'cases' yielding a final analytical sample of 3955 individuals. An index age, equivalent to the age at death of their respective cases' was set for each control. Hypnotic drug purchases were followed from the Finnish nationwide register during a 36-month run-up period before the date of death/index date. The prevalence and incidence of hypnotic purchases were compared between cases and matched controls. Moreover, latent developmental trajectories of purchases were modelled and their relations with specific and all-cause death risks were analysed. RESULTS: An increasing difference between cases and controls was observed as regards the use of hypnotic drugs. During the last 30 months before the date of death/index date, the rate ratio of incident purchases between cases and controls was 2.37 (95% CL, 1.79-3.12) among older and 3.61 (95% CL, 2.37-5.89) among younger individuals. The developmental trajectories of hypnotic drug purchases were differently and by interpretation plausibly associated with specific mortality risks. CONCLUSIONS: In most cases the association between hypnotics and mortality risk is created by symptomatic treatment when death is approaching.

Does removal of work stress explain improved sleep following retirement? The Finnish Retirement and Aging study.

STUDY OBJECTIVES: Relief from work stress has been hypothesized to explain improvements in sleep duration and quality following retirement, but this has not been confirmed with longitudinal studies. By using repeat sleep data, we examined the role of removal of work-related stressors in changes in sleep at retirement. METHODS: The study population consisted of 2,053 participants from the Finnish Retirement and Aging study. Participants' sleep duration, sleep difficulties (difficulties falling asleep, difficulties maintaining sleep, waking up too early in the morning, nonrestorative sleep), daytime tiredness, and sleep loss due to worry were assessed using surveys conducted once a year before and after retirement (average number of repeat surveys 3.5 [range 2-5] per participant). We used Poisson regression with generalized estimating equations to examine the associations between work-related stressors (job strain, low work time control, effort-reward imbalance, and organizational injustice) and changes in sleep at retirement. RESULTS: An increase in sleep duration and decrease in waking up too early in the morning, nonrestorative sleep, daytime tiredness, and sleep loss due to worry were observed shortly after retirement. No systematic associations across the work-related stressors and changes in sleep characteristics were observed. Higher number of work-related stressors before retirement was not associated with a greater magnitude of favorable changes in any of the postretirement sleep characteristics investigated. CONCLUSIONS: This longitudinal study suggests that perceived sleep improves shortly after retirement and that these changes are mainly driven by factors other than relief from work stress.

Alexithymia and somatization in general population.

OBJECTIVE: Even though the association between alexithymia and somatization seems plausible according to several studies with selected populations, it has not been verified in carefully controlled and nationally representative population studies. We conducted such a study to find out whether alexithymia is associated with somatization at population level. METHODS: This study was a part of the Finnish Health 2000 Study. The nationally representative sample comprised 5129 subjects aged 30 to 97 years. Alexithymia was measured with the 20-item Toronto Alexithymia Scale (TAS-20) and somatic symptom reporting with the 12-item somatization scale derived from the Hopkins Symptom Checklist. Sociodemographic and health-related variables, including depressive and anxiety disorders, and physician verified somatic diagnoses, were treated as confounders in multivariate analyses. RESULTS: Alexithymia was associated with somatization independently of somatic diseases, depression and anxiety and confounding sociodemographic variables. The TAS-20 factor scale "Difficulties Identifying Feelings" was the strongest common denominator between alexithymia and somatization. CONCLUSIONS: This was the first time the independent association between alexithymia and somatization was established in a large, nationally representative nonclinical sample of both young and old adults with and without mental disorders and somatic diseases.