Risk factors for incident chronic insomnia: a general population prospective study

Association of the melatonin circadian rhythms with clock 3111T/C gene polymorphism in Caucasian and Asian menopausal women with insomnia

A comparative analysis of melatonin circadian rhythms in Caucasian (incoming population) and Asian (indigenous population) menopausal women with/without sleep disorders depending on the genotype of Clock 3111T/C gene polymorphism was realized.The melatonin level in the saliva was determined four times a day (6:00-7:00, 12:00-13:00, 18:00-19:00, 23:00-00:00 h). The Caucasian women-carriers of the TT-genotype with insomnia as compared to control group-had a higher morning melatonin level and a lower night melatonin level. The Asian women with TT-genotype and insomnia had a lower levels of melatonin as compared to control at daytime, evening and night. A significantly higher melatonin level in the early morning hours was detected in the Caucasian women-carriers of the TT-genotype with insomnia as compared to group womencarriers of the minor 3111C-allele. There were no statistically significant differences in the circadian rhythms of melatonin in the Asian women depending on the genotype of the Clock 3111T/C polymorphism. An assumption with respect to the protective role of the minor allele 3111C in the development of insomnia associated with the displacement of melatonin circadian rhythms in the representatives of the incoming population was made.

Insomnia symptoms and sleep duration and their combined effects in relation to associations with obesity and central obesity

OBJECTIVE

Previous studies have shown that both sleep duration and insomnia have an impact on obesity and central obesity. However, studies of the joint effects of these sleep disorders are still sparse.

METHODS

The present study utilized data from the Swedish EpiHealth cohort study. Participants (45-78 y) were asked to fill out an internet-based questionnaire. Body mass index (BMI) and central obesity (calculated from waist circumference) were based on measured data.

RESULTS

A total of 18,823 participants (mean age = 60 ys) were included in this study. The reported prevalence of short (<6 h/night) and long (>9 h/night) sleep duration was 8% and 4% respectively, and insomnia symptoms was 19%. Of the study population, 16% were obese (BMI ≥ 30 kg/m²) and 40% had central obesity. There was a U-shaped association between sleep duration and obesity and central obesity, and significant associations between insomnia symptoms and obesity. When stratifying sleep duration by concurrent insomnia symptoms, there were associations (odds ratios, (95% confidence intervals)) between the combination of both short (1.48, (1.22-1.80)) and long sleep duration (1.77 (1.00-3.16)) with insomnia symptoms and obesity and central obesity (1.36 (1.16-1.61) and 2.44 (1.41-3.24) respectively). However, there was no significant association between insomnia symptoms and obesity or central obesity in participants with normal sleep duration. For central obesity there was an association with long sleep duration regardless of insomnia symptoms, while the association with short sleep duration was significant only if insomnia symptoms were present.

CONCLUSIONS

Both short and long sleep duration, as well as insomnia symptoms, are associated with obesity and central obesity. There is an important joint effect of sleep duration and insomnia symptoms and there is no association between insomnia symptoms and obesity, as long as a normal sleeping time can be attained. This indicates that sleep duration rather than insomnia symptoms per se is of importance for the relationship between sleep and obesity.

Genetic Ancestry for Sleep Research: Leveraging Health Inequalities to Identify Causal Genetic Variants

Recent evidence has highlighted the health inequalities in sleep behaviors and sleep disorders that adversely affect outcomes in select populations, including African-American and Hispanic-American subjects. Race-related sleep health inequalities are ascribed to differences in multilevel and interlinked health determinants, such as sociodemographic factors, health behaviors, and biology. African-American and Hispanic-American subjects are admixed populations whose genetic inheritance combines two or more ancestral populations originating from different continents. Racial inequalities in admixed populations can be parsed into relevant groups of mediating factors (environmental vs genetic) with the use of measures of genetic ancestry, including the proportion of an individual's genetic makeup that comes from each of the major ancestral continental populations. This review describes sleep health inequalities in African-American and Hispanic-American subjects and considers the potential utility of ancestry studies to exploit these differences to gain insight into the genetic underpinnings of these phenotypes. The inclusion of genetic approaches in future studies of admixed populations will allow greater understanding of the potential biological basis of race-related sleep health inequalities.

Nocturnal insomnia symptoms and stress-induced cognitive intrusions in risk for depression: A 2-year prospective study

Nearly half of US adults endorse insomnia symptoms. Sleep problems increase risk for depression during stress, but the mechanisms are unclear. During high stress, individuals having difficulty falling or staying asleep may be vulnerable to cognitive intrusions after stressful events, given that the inability to sleep creates a period of unstructured and socially isolated time in bed. We investigated the unique and combined effects of insomnia symptoms and stress-induced cognitive intrusions on risk for incident depression. 1126 non-depressed US adults with no history of DSM-5 insomnia disorder completed 3 annual web-based surveys on sleep, stress, and depression. We examined whether nocturnal insomnia symptoms and stress-induced cognitive intrusions predicted depression 1y and 2y later. Finally, we compared depression-risk across four groups: non-perseverators with good sleep, non-perseverators with insomnia symptoms, perseverators with good sleep, and perseverators with insomnia symptoms. Insomnia symptoms (β = .10-.13, p < .001) and cognitive intrusions (β = .19-.20, p < .001) predicted depression severity 1y and 2y later. Depression incidence across 2 years was 6.2%. Perseverators with insomnia had the highest rates of depression (13.0%), whereas good sleeping non-perseverators had the lowest rates (3.3%, Relative Risk = 3.94). Perseverators with sleep latency >30 m reported greater depression than good sleeping perseverators (t = 2.09, p < .04). Cognitive intrusions following stress creates a depressogenic mindset, and nocturnal wakefulness may augment the effects of cognitive arousal on depression development. Poor sleepers may be especially vulnerable to cognitive intrusions when having difficulty initiating sleep. As treatable behaviors, nighttime wakefulness and cognitive arousal may be targeted to reduce risk for depression in poor sleepers.

Withdrawn and wired: Problematic internet use accounts for the link of neurotic withdrawal to sleep disturbances

Although neuroticism is the strongest personality predictor of sleep disturbance, it is not clear whether dysphoric (Withdrawal) or angry (Volatility) aspect of neuroticism is more important and whether problematic technology use plays an intervening role. To this end, this study examined distinct contributions of neurotic withdrawal and volatility in predicting self-reported sleep disturbance while testing the mediating role of problematic internet use. Methods: One-hundred and fourty-three college students completed an online survey that included measures of neuroticism, sleep quality, and problematic internet use. Results: Although both aspects of neuroticism predicted poor sleep, Withdrawal emerged as a stronger and the only unique predictor. Furthermore, problematic internet use explained a portion of Withdrawal's relationship to worse sleep, especially nighttime and daytime disturbances. Discussion: The findings suggest that dysphoric rather than angry features of neuroticism are more important for sleep problems and that the problematic use of modern technology may be an important contributing factor.

Organized Social Activity, Physical Exercise, and the Risk of Insomnia Symptoms Among Community-Dwelling Older Adults

Objectives: To compare the risk of insomnia symptoms among community-dwelling older adults who participated and did not participate in organized social activity and physical exercise. Design: Secondary data analysis of a prospective cohort study. Material and Methods: Community-dwelling older adults ≥65 years of age with no insomnia symptoms at baseline were included in the study. Participants were followed up yearly for 3 years. Insomnia symptoms, social activity, and physical exercise status of study participants were assessed at baseline and during follow-up. Results: Study participants who reported engaging in organized social activity and low-intensity physical exercise and organized social activity and high-intensity physical exercise were less likely to report insomnia symptoms during follow-up compared with those who did not engage in any activity. Conclusion: These results suggest beneficial effect of organized social activity and physical exercise in maintaining sleep quality in old age.

Sex-specific associations of different anthropometric indices with acute and chronic insomnia

Background

Sleep disorders, including insomnia, are risk factors for weight gain. However, few epidemiological studies have investigated the association of anthropometric markers with insomnia as an outcome.

Methods

In this observational, cross-sectional study, we assessed the association of 3 different anthropometric indices with acute and chronic insomnia. We used data from 13 389 French adults (mean age= 51.9 ± 13.1 years; 70.3% women) enrolled in the NutriNet-Santé-Biobank cohort. Body weight, height, waist and hip circumference were measured once during a clinic visit (2011-14). Body mass index (BMI), waist circumference (WC) and waist-to-hip ratio (WHR) were the main predictors. Acute (past 8 days) and chronic (≥3 months) insomnia were assessed in 2014 via a self-report questionnaire. We fit multivariable logistic regression models providing odds ratios (OR) and 95% confidence intervals (CI).

Results

Overweight (25.0 ≤ BMI < 30.0 kg/m2) and general obesity (BMI ≥ 30.0 kg/m2) appeared to have an inverse association with acute insomnia only among men (overweight: OR= 0.80, 95% CI: 0.70, 0.92; obesity: OR= 0.78, 95% CI: 0.63, 0.98). Obesity assessed by BMI and WHR appeared to be positively associated with chronic insomnia only among women (BMI: OR= 1.23, 95% CI: 1.04, 1.45; WHR: OR= 2.24, 95% CI: 1.07, 4.72). WC did not display any significant associations in either sex.

Conclusions

These cross-sectional results revealed sex-specific associations of overweight/obesity with different types of insomnia, and merit confirmation longitudinally with objectively assessed sleep parameters. Nonetheless, the findings reinforce the critical importance of joint health behaviour promotion.

Cognitive and affective functions associated with insomnia: a population-based study

OBJECTIVES

The number of patients with insomnia is rapidly increasing as society ages. The influence of insomnia on cognitive, affective, and activities of daily living (ADL) functions has not been fully studied.

METHODS

Participants were 142 residents of a local super-aged community who underwent health check-ups provided by the local government. Participants completed cognitive, affective and ADL function tests including the MMSE. We divided participants into two subgroups based on Athens Insomnia Scale (AIS) scores (AIS ≤3 and AIS ≥4) and compared cognitive, affective, and ADL functions by sex and age.

RESULTS

Subjective insomnia (AIS ≥4) was found in 36.2% of participants and was more frequent in females than males. No differences were found in cognitive function between the AIS subgroups. For both sexes, Geriatric Depression Scale scores were significantly higher in the AIS ≥4 subgroup than the AIS ≤3 subgroup. Apathy Scale scores were significantly higher in males in the AIS ≥4 subgroup. Of the AIS subscales, 'sleepiness during the day' was significantly higher in females than males (**p < 0.01), especially in those aged  ≥75 years (**p < 0.01). This group of older females also showed a significantly lower Trail Making Test scores (*p < 0.05).

DISCUSSION

Insomnia was present in 36.2% of the population in a Japanese super-aged community. Those with insomnia showed more depressive symptoms (both sexes) and males showed more apathy. The most distinct characteristic of females aged  ≥75 years was a high frequency of daytime sleepiness, possibly related to a decline in attention and executive function.

Physical activity, smoking, and the incidence of clinically diagnosed insomnia

OBJECTIVE

This study was designed to examine the independent and combined associations of physical activity and smoking on the incidence of doctor-diagnosed insomnia using a nationally representative sample over seven years, taking into account other relevant covariates.

METHODS

Participants aged 18 years or older in the 2005 Taiwan National Health Interview Survey (NHIS) with links to National Health Insurance (NHI) claim data between 2005 and 2012 and without diagnosed insomnia before 2005, were selected into this study (n = 12,728). Participants were classified as having insomnia with International Classification of Diseases, Ninth Revision (ICD-9) CM codes 307.41, 307.42, or 780.52. Self-reported smoking status and frequency, duration, and types of leisure-time and non-leisure-time physical activities were collected. Metabolic equivalent (MET) intensity levels for each activity were assigned, and weekly energy expenditure of each activity was calculated and summed.

RESULTS

Inactive participants had a higher risk of incident insomnia [hazard ratio (HR) = 1.22, 95% confidence interval (CI) = 1.06-1.42, p = 0.007] than the active group, and ever-smokers were more likely to have incident insomnia than never smokers (HR = 1.45, 95% CI = 1.20-1.76, p < 0.001). Compared with the nonsmoker/active group, the ever-smoker/inactive group had a higher risk of incident insomnia (HR = 1.78, 95% CI = 1.41-2.25, p < 0.001). Sensitivity analyses excluding individuals diagnosed with other sleep disorders or mental disorders yielded similar results, with the ever-smoker/inactive group having the highest risk of insomnia.

CONCLUSIONS

Inactive adults and smokers are at higher risk for incident insomnia, highlighting the importance of a healthy lifestyle and pointing to strategies such as encouraging smoking cessation and physical activity to avoid insomnia among adults.

Effect of Six-Month Diet Intervention on Sleep among Overweight and Obese Men with Chronic Insomnia Symptoms: A Randomized Controlled Trial

Growing evidence suggests that diet alteration affects sleep, but this has not yet been studied in adults with insomnia symptoms. We aimed to determine the effect of a six-month diet intervention on sleep among overweight and obese (Body mass index, BMI ≥ 25 kg/m²) men with chronic insomnia symptoms. Forty-nine men aged 30–65 years with chronic insomnia symptoms were randomized into diet (n = 28) or control (n = 21) groups. The diet group underwent a six-month individualized diet intervention with three face-to-face counseling sessions and online supervision 1–3 times per week; 300–500 kcal/day less energy intake and optimized nutrient composition were recommended. Controls were instructed to maintain their habitual lifestyle. Sleep parameters were determined by piezoelectric bed sensors, a sleep diary, and a Basic Nordic sleep questionnaire. Compared to the controls, the diet group had shorter objective sleep onset latency after intervention. Within the diet group, prolonged objective total sleep time, improved objective sleep efficiency, lower depression score, less subjective nocturnal awakenings, and nocturia were found after intervention. In conclusion, modest energy restriction and optimized nutrient composition shorten sleep onset latency in overweight and obese men with insomnia symptoms.

Changes in ischemic stroke occurrence following daylight saving time transitions

BACKGROUND

Circadian rhythm disruption has been associated with increased risk of ischemic stroke (IS). Daylight saving time (DST) transitions disrupt circadian rhythms and shifts the pattern of diurnal variation in stroke onset, but effects on the incidence of IS are unknown.

METHODS

Effects of 2004-2013 DST transitions on IS hospitalizations and in-hospital mortality were studied nationwide in Finland. Hospitalizations during the week following DST transition (study group, n = 3033) were compared to expected hospitalizations (control group, n = 11,801), calculated as the mean occurrence during two weeks prior to and two weeks after the index week.

RESULTS

Hospitalizations for IS increased during the first two days (Relative Risk 1.08; CI 1.01-1.15, P = 0.020) after transition, but difference was diluted when observing the whole week (RR 1.03; 0.99-1.06; P = 0.069). Weekday-specific increase was observed on the second day (Monday; RR 1.09; CI 1.00-1.90; P = 0.023) and fifth day (Thursday; RR 1.11; CI 1.01-1.21; P = 0.016) after transition. Women were more susceptible than men to temporal changes during the week after DST transitions. Advanced age (>65 years) (RR 1.20; CI 1.04-1.38; P = 0.020) was associated with increased risk during the first two days, and malignancy (RR 1.25; CI 1.00-1.56; P = 0.047) during the week after DST transition.

CONCLUSIONS

DST transitions appear to be associated with an increase in IS hospitalizations during the first two days after transitions but not during the entire following week. Susceptibility to effects of DST transitions on occurrence of ischemic stroke may be modulated by gender, age and malignant comorbidities.

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.

Role of neuroinflammation and sex hormones in war-related PTSD

The susceptibility to develop posttraumatic stress disorder (PTSD) is greatly influenced by both innate and environmental risk factors. One of these factors is gender, with women showing higher incidence of trauma-related mental health disorders than their male counterparts. The evidence so far links these differences in susceptibility or resilience to trauma to the neuroprotective actions of sex hormones in reducing neuroinflammation after severe stress exposure. In this review, we discuss the impact of war-related trauma on the incidence of PTSD in civilian and military populations as well as differences associated to gender in the incidence and recovery from PTSD. In addition, the mutually influencing role of inflammation, genetic, and sex hormones in modulating the consequences derived from exposure to traumatic events are discussed in light of current evidence.

The relative association of obstructive sleep apnea, obesity and excessive daytime sleepiness with incident depression: a longitudinal, population-based study

BACKGROUND

It is postulated that obstructive sleep apnea (OSA) is a risk factor for the development of depression. However, obesity and excessive daytime sleepiness (EDS) are associated with both OSA and depression. The goal of this study was to examine the relative contribution of OSA, obesity and EDS to incident depression.

METHODS

A representative random sample of 1137 adults without depression from the Penn State Adult Cohort was followed up after 7.5 years. All subjects underwent a full medical examination and polysomnography at baseline. OSA was defined as an apnea/hypopnea index (AHI) ⩾5, overweight as a body mass index (BMI) of 25-29.9 kg m(-)(2), obesity as a BMI⩾30 kg m(-)(2) and EDS as moderate-to-severe drowsiness/sleepiness and/or irresistible sleep attacks.

RESULTS

Overweight, obesity and EDS were associated with incident depression, whereas OSA alone was not. Overweight was associated with incident depression in women, while obesity and EDS were associated with incident depression in both genders. The association of overweight and obesity with incident depression was independent of premorbid emotional distress, while that of EDS was not. The association between BMI and EDS with incident depression was stronger in women 20-40 years old. The severity of EDS predicted incident depression in those with OSA, while AHI or oxygen desaturation did not.

CONCLUSIONS

Overweight, obesity and EDS are the main predictors of incident depression. Obesity may be linked to depression through psychobiological mechanisms, while EDS may be an early sign of depression. Obesity should be a target of our preventative strategies for depression.

The role of psychiatric and somatic conditions in incidence and persistence of insomnia: a longitudinal, community study

OBJECTIVE

The objective was to investigate the role of psychiatric and somatic conditions in incident and persistent insomnia.

DESIGN

This was a prospective study with 3 measurement points over 1.5years.

SETTING

The participants were sent a survey to their home addresses.

PARTICIPANTS

A survey was sent out to 5000 random individuals (18-70 years) in 2 Swedish counties. To those who returned the baseline questionnaire (n=2333), 2 follow-up surveys (6 and 18months later) were sent out and completed by 1887 and 1795 individuals, respectively.

MEASUREMENTS

The survey contained questions about sociodemographic factors and insomnia symptomatology, the Hospital Anxiety and Depression Scale, and items assessing 12 forms of somatic conditions (eg, heart disease and headache).

RESULTS

Baseline depression, headache, and number of psychiatric and somatic conditions were found to be independent risk factors for incident insomnia. Also, deterioration in depression and heart disease status and increased number of conditions over time increased the risk for insomnia incidence. Anxiety; depression; pain in neck, back, or shoulders; and headache at baseline were found to significantly discriminate between those with persistent insomnia and those with persistent normal sleep. Those with persistent insomnia also reported a higher number of conditions relative to those with persistent normal sleep. None of the psychiatric or somatic conditions were found to be associated with persistence of insomnia relative to remission of insomnia.

CONCLUSION

The current study suggests that both psychiatric and somatic conditions are involved in the incidence but not in the persistence of insomnia. Clinical and theoretical implications of the results are discussed.

Sleep system sensitization: evidence for changing roles of etiological factors in insomnia

OBJECTIVES

To test for sensitization of the sleep system in response to insomnia development and major life stress. In addition, to evaluate the impact on depression and anxiety associated with sleep system sensitization.

METHODS

A longitudinal study with three annual assessments. The community-based sample included 262 adults with no history of insomnia or depression who developed insomnia one year after baseline (67.6% female; 44.0 ± 13.4 yr). Measures included the Ford Insomnia Response to Stress Test to assess sleep reactivity, Quick Inventory of Depressive Symptomatology, and Beck Anxiety Inventory. Insomnia classification was based on DSM-IV criteria. Sleep system sensitization was operationally defined as significant increases in sleep reactivity.

RESULTS

Sensitization of the sleep system was observed from baseline to insomnia onset at 1-yr follow-up among insomniacs with low premorbid vulnerability (p < 0.001), resulting in 68.3% of these individuals re-classified as highly sleep reactive. Major life stress was associated with greater sleep system sensitization (p = 0.02). Results showed that sleep reactivity at 2-yr follow-up remained elevated among those with low premorbid vulnerability, even after insomnia remission (p < 0.01). Finally, analyses revealed that increases in sleep reactivity predicted greater depression (p < 0.001) and anxiety (p < 0.001) at insomnia onset. The impact of sensitization on depression was stable at 2-yr follow-up (p = 0.01).

CONCLUSIONS

Evidence supports sensitization of the sleep system as a consequence of insomnia development and major life stress among individuals with low premorbid sleep reactivity. Sleep system sensitization may serve as a mechanism by which insomnia is perpetuated. Harmful effects of the sensitization process may increase risk for insomnia-related depression and anxiety.

Identifying At-Risk Individuals for Insomnia Using the Ford Insomnia Response to Stress Test

STUDY OBJECTIVES

A primary focus of the National Institute of Mental Health's current strategic plan is "predicting" who is at risk for disease. As such, the current investigation examined the utility of premorbid sleep reactivity in identifying a specific and manageable population at elevated risk for future insomnia.

METHODS

A community-based sample of adults (n = 2,892; 59.3% female; 47.9 ± 13.3 y old) with no lifetime history of insomnia or depression completed web-based surveys across three annual assessments. Participants reported parental history of insomnia, demographic characteristics, sleep reactivity on the Ford Insomnia in Response to Stress Test (FIRST), and insomnia symptoms. DSM-IV diagnostic criteria were used to determine insomnia classification.

RESULTS

Baseline FIRST scores were used to predict incident insomnia at 1-y follow-up. Two clinically meaningful FIRST cutoff values were identified: FIRST ≥ 16 (sensitivity 77%; specificity 50%; odds ratio [OR] = 2.88, P < 0.001); and FIRST ≥ 18 (sensitivity 62%; specificity 67%; OR = 3.32, P < 0.001). Notably, both FIRST cut-points outperformed known maternal (OR = 1.49-1.59, P < 0.01) and paternal history (P = NS) in predicting insomnia onset, even after controlling for stress exposure and demographic characteristics. Of the incident cases, insomniacs with highly reactive sleep systems reported longer sleep onset latencies (FIRST ≥ 16: 65 min; FIRST ≥ 18: 68 min) than participants with nonreactive insomnia (FIRST < 16: 37 min; FIRST < 18: 44 min); these groups did not differ on any other sleep parameters.

CONCLUSIONS

The current study established a cost- and time-effective strategy for identifying individuals at elevated risk for insomnia based on trait sleep reactivity. The FIRST accurately identifies a focused target population in which the psychobiological processes complicit in insomnia onset and progression can be better investigated, thus improving future preventive efforts.

Sleep as a potential fundamental contributor to disparities in cardiovascular health

Optimal sleep is integral to health but is commonly not obtained. Despite its wide-ranging public health impact, sleep health is considered only rarely by policy makers, employers, schools, and others whose policies and structures can adversely affect sleep. An inadequate duration of sleep and poor-quality sleep are prevalent in minority and low-income populations, and may be fundamental to racial and socioeconomic status inequities that contribute to a range of health conditions, including cardiovascular disease (CVD). This review examines the relationship between sleep and disparities in CVD. We describe the public health importance of sleep and the role of sleep duration, as well as the two most common disorders (sleep apnea and insomnia) as risk factors for a number of chronic diseases. We use a multilevel model focused on population health and health disparities, which is based on the notion that individual behaviors, such as sleep, are influenced by complex and dynamic interrelations among individuals and their physical and social environments. We also describe modifiable factors that contribute to insufficient sleep and circadian misalignment, propose potential interventions in various sectors (e.g., neighborhoods, schools, workplaces) that can address social structures that contribute to disparities, and recommend areas for future research. Integrating sleep into public health research will identify novel approaches for closing gaps in health disparities.

[Sleep duration and metabolism]

Sleep duration has gradually diminished during the last decade while obesity and type 2 diabetes have become epidemics. Experimental sleep curtailment leads to increased appetite, hormonal disturbances and, especially, insulin resistance. Numerous epidemiological studies have therefore examined whether habitual short sleep is associated with obesity and type 2 diabetes. A large majority of cross-sectional studies have confirmed an association between short, and also long sleep duration and obesity in adults more than in the elderly. Short sleep is strongly associated to obesity in children and adolescents. Prospective studies, including studies in children, are not conclusive with regard to the effect of short sleep on the incidence of obesity. Both short and long sleep durations are associated with diabetes, but only short sleep duration seems predictive of future diabetes. Insomnia seems to be a strong contributor to short sleep duration but the association of insomnia with obesity is not clear. Insomnia is associated with type 2 diabetes and also predictive of a higher incidence. Other studies have shown that short sleep duration and insomnia are associated with, and sometime predictive of, other components of the metabolic syndrome, especially hypertension and the risk of coronary disease. The treatment of short sleep duration and insomnia with regard to their effects on the metabolic syndrome merits further study.

Gastrointestinal symptoms negatively impact on sleep quality among obese individuals: a population-based study

BACKGROUND

Reduced sleep quality has been linked to obesity; however, no studies have assessed the impact of gastrointestinal (GI) symptoms on sleep quality among obese individuals. This study aims to determine the role of gastrointestinal symptoms on sleep among obese individuals in a community-based sample.

METHODS

A validated questionnaire was sent to 5000 randomly selected subjects in Western Sydney, Australia. Assessed were five GI symptoms that might wake individuals from sleep (abdominal pain, diarrhea, chest pain, acid regurgitation, and heartburn). Sleep quality was measured using the validated Pittsburgh Sleep Quality Index (PSQI). Additional measures included socioeconomic status (SES) and body mass index (BMI).

RESULTS

The response rate was 60 %. There were 647 (25.13 %) obese individuals. Prevalence estimates for general quality of sleep were reported as very good (18.51 %), fairly good (53.19 %), fairly bad (20.68 %), and very bad (7.62 %). Obese individuals reported less hours of actual sleep than nonobese individuals (OR = 0.87; 95 % CI 0.81-0.94). Quality of sleep was worse for obese compared to nonobese individuals (OR = 1.25; 95 % CI 1.12-1.40). Univariate analysis found that all GI symptoms were more likely to wake obese people from their sleep; however, only two GI symptoms (chest pain: OR = 1.60; 95 % CI 1.25-2.04) and (acid regurgitation: OR = 1.27; 95 % CI 1.05-1.53) were independent predictors of sleep disturbance.

CONCLUSIONS

Gastrointestinal symptoms did not predict waking in nonobese individuals. Chest pain and acid regurgitation are major GI symptoms associated with waking obese individuals from sleep. Overall, obese individuals have a worse quality of sleep compared to nonobese individuals.

Symptoms of Depression and Difficulty Initiating Sleep from Early Adolescence to Early Adulthood: A Longitudinal Study

STUDY OBJECTIVES

To assess the direction of the relationship and degree of shared associations between symptoms of depression and difficulty initiating sleep (DIS) from early adolescence to early adulthood.

DESIGN

Cross-sectional and longitudinal assessment of the symptoms of depression-DIS association from early adolescence (age 13 y) to early adulthood (age 23 y).

SETTING

Hordaland, Norway.

PARTICIPANTS

There were 1,105 individuals (55% male) who took part in the Norwegian Longitudinal Health Behaviour Study (NLHB) and participated at least once across seven data collection waves during the years 1990-2000.

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

Characteristic data were obtained during the first assessment. Symptoms of depression and instances of DIS were assessed during each data collection wave. Symptoms of depression and DIS were associated in all data waves, and one-step cross-lagged bivariate correlations were significant and comparatively high for both factors. Structural equation modelling indicated that DIS and symptoms of depression at wave 1 remain relatively stable across waves (all P < 0.001), and a significant and consistent unidirectional cross-lagged effect was noted running from symptoms of depression to DIS from early adolescence to early adulthood. DIS is only marginally and inconsistently associated with the lagged symptoms of depression score across waves.

CONCLUSIONS

These results suggest that symptoms of depression established in early adolescence are a moderate predictor of difficulty initiating sleep (DIS) in early adulthood, whereas the reverse association of DIS predicting depression was not convincingly supported. These findings are in contrast to previous findings that suggest sleep problems as a risk factor for the later development of depression.

Insomnia disorder

Insomnia disorder affects a large proportion of the population on a situational, recurrent or chronic basis and is among the most common complaints in medical practice. The disorder is predominantly characterized by dissatisfaction with sleep duration or quality and difficulties initiating or maintaining sleep, along with substantial distress and impairments of daytime functioning. It can present as the chief complaint or, more often, co-occurs with other medical or psychiatric disorders, such as pain and depression. Persistent insomnia has been linked with adverse long-term health outcomes, including diminished quality of life and physical and psychological morbidity. Despite its high prevalence and burden, the aetiology and pathophysiology of insomnia is poorly understood. In the past decade, important changes in classification and diagnostic paradigms have instigated a move from a purely symptom-based conceptualization to the recognition of insomnia as a disorder in its own right. These changes have been paralleled by key advances in therapy, with generic pharmacological and psychological interventions being increasingly replaced by approaches that have sleep-specific and insomnia-specific therapeutic targets. Psychological and pharmacological therapies effectively reduce the time it takes to fall asleep and the time spent awake after sleep onset, and produce a modest increase in total sleep time; these are outcomes that correlate with improvements in daytime functioning. Despite this progress, several challenges remain, including the need to improve our knowledge of the mechanisms that underlie insomnia and to develop more cost-effective, efficient and accessible therapies.

Insomnia and incident depression: role of objective sleep duration and natural history

Longitudinal studies that have examined the association of insomnia with incident depression using objective sleep measures are very limited. The aim of this study was to examine the predictive role of the severity of insomnia for incident depression in a general population sample using psychometric and polysomnographic data. From a random, general population sample of 1741 individuals of the Penn State Adult Cohort, 1137 adults without depression were followed up with a structured telephone interview after 7.5 years. All subjects completed a full medical evaluation, 1-night polysomnogram and Multiphasic Minnesota Personality Inventory at baseline. The incidence of depression was 15%. Poor sleep (odds ratio = 1.5, P = 0.001) and insomnia (odds ratio = 1.9, P = 0.031) were significantly associated with incident depression. The odds of incident depression were highest (odds ratio = 2.2, P = 0.019) in insomnia with objective short sleep duration and independent of Multiphasic Minnesota Personality Inventory Ego Strength scores, an index of poor coping resources. The persistence of insomnia and worsening of poor sleep into insomnia significantly increased the odds of incident depression (odds ratios ranged from 1.8 to 6.3), whereas their full remission did not (odds ratio ranged from 1.2 to 1.8). Insomnia with short sleep duration is associated with incident depression independent of poor coping resources, whereas the association of insomnia with normal sleep duration with incident depression was mediated by poor coping resources. Persistence and worsening of poor sleep or insomnia, but not their full remission, are significant predictors of incident depression. These data suggest that there is a significant relationship between the severity of insomnia and incident depression.

The effect of poor sleep quality on mood outcome differs between men and women: A longitudinal study of bipolar disorder

BACKGROUND

Sleep disturbance is bi-directionally related to mood de-stabilization in bipolar disorder (BD), and sleep quality differs in men and women. We aimed to determine whether perception of poor sleep quality would have a different effect on mood outcome in men versus women.

METHODS

We assessed association between sleep quality (Pittsburgh Sleep Quality Index (PSQI)) at study intake and mood outcome over 2 years in subjects from the Prechter Longitudinal Study of Bipolar Disorder (N=216; 29.6% males). The main outcome measure was the severity, variability, and frequency of mood episodes measured by self-report over 2 years of follow-up. Multivariable linear regression models stratified by sex examined the relationship between PSQI with mood outcomes, while age, stressful life events, mood state and neuroticism at baseline were controlled.

RESULTS

In women, poor sleep quality at baseline predicted increased severity (B=0.28, p<0.001) and frequency of episodes (B=0.32, p<0.001) of depression, and poor sleep quality was a stronger predictor than baseline depression; poor sleep quality predicted increased severity (B=0.19, p<0.05) and variability (B=0.20, p<0.05) of mania, and frequency of mixed episodes (B=0.27, p<0.01). In men, baseline depression and neuroticism were stronger predictors of mood outcome compared to poor sleep quality.

LIMITATIONS

We measured perception of sleep quality, but not objective changes in sleep.

CONCLUSIONS

In a longitudinal study of BD, women reported poorer perceived sleep quality than men, and poor sleep quality predicted worse mood outcome in BD. Clinicians should be sensitive to addressing sleep complaints in women with BD early in treatment to improve outcome in BD.

Gender Differences in Real-Home Sleep of Young and Older Couples

STUDY OBJECTIVES

To understand gender differences in sleep quality, architecture and duration of young healthy couples in comparison to older couples in their natural sleep environment.

DESIGN

Sleep was monitored in a naturalistic setting using a headband sleep monitoring device over a period of two weeks for young couples and home polysomnography for the older couples.

PARTICIPANTS

Ten heterosexual young couples (male mean age: 28.2±1.0[SD] years/female mean age: 26.8±0.9 years) and 14 older couples (male mean age: 59.3±9.6 years/female mean age: 58.8±9.1 years).

MEASUREMENTS AND RESULTS

In the young couples, total sleep time (395±66 vs. 367±54 min., p<0.05), sleep efficiency (97.0±3.0 vs. 91.1±7.9, p<0.001), and % REM (31.1±4.8 vs. 23.6±5.5, p<0.001) in males was higher than in females. In contrast, % light sleep (51.7±7.1 vs. 59.7±6.7, p<0.001) and number of arousals (2.9±1.9 vs. 5.3±1.9, p<0.001) were lower. These differences persisted after controlling for evening mood and various evening pre-sleep activities. In the older couples, there were no differences between genders. In addition, children in the household adversely impacted sleep.

CONCLUSIONS

In couples recorded in the home, young males slept longer and had better sleep quality than young females. This difference appears to dissipate with age. In-home assessment of couples can aid in understanding of gender differences in sleep and how they are affected by age and social environment.

Natural history of excessive daytime sleepiness: role of obesity, weight loss, depression, and sleep propensity

STUDY OBJECTIVES

Excessive daytime sleepiness (EDS) is highly prevalent in the general population and is associated with occupational and public safety hazards. However, no study has examined the clinical and polysomnographic (PSG) predictors of the natural history of EDS.

DESIGN

Representative longitudinal study.

SETTING

Sleep laboratory.

PARTICIPANTS

From a random, general population sample of 1,741 individuals of the Penn State Adult Cohort, 1,395 were followed up after 7.5 years.

MEASUREMENTS AND RESULTS

Full medical evaluation and 1-night PSG at baseline and standardized telephone interview at follow-up. The incidence of EDS was 8.2%, while its persistence and remission were 38% and 62%, respectively. Obesity and weight gain were associated with the incidence and persistence of EDS, while weight loss was associated with its remission. Significant interactions between depression and PSG parameters on incident EDS showed that, in depressed individuals, incident EDS was associated with sleep disturbances, while in non-depressed individuals, incident EDS was associated with increased physiologic sleep propensity. Diabetes, allergy/ asthma, anemia, and sleep complaints also predicted the natural history of EDS.

CONCLUSIONS

Obesity, a disorder of epidemic proportions, is a major risk factor for the incidence and chronicity of EDS, while weight loss is associated with its remission. Interestingly, objective sleep disturbances predict incident EDS in depressed individuals, whereas physiologic sleep propensity predicts incident EDS in those without depression. Weight management and treatment of depression and sleep disorders should be part of our public health policies.

Sleeping problems in Chinese illicit drug dependent subjects

BACKGROUND

Illicit drug use/dependence has been recognized as a major problem. Clinical studies demonstrate that poor sleep quality is associated with increased frequency of drug use and relapse. However, few studies have addressed the issue of sleep quality among illicit drug dependent subjects.

METHODS

This cross-sectional study explored sleep quality in drug dependent subjects in China. We studied 2178 illicit drug dependent subjects from drug rehabilitation centres in Changsha and 2236 non-drug-using subjects, all of whom completed the self-report Pittsburgh Sleep Quality Index (PSQI).

RESULTS

We found that the prevalence of sleep disturbance was much higher in drug users (68.5%, PSQI >5; specifically, 80.24% in heroin users, 54.16% in methamphetamine users and 81.98% in ketamine users with PSQI >5) than non-users (26.4%, PSQI >5). Drug users had approximately twice the sleep latency than nondrug users (37.7 minutes V.S 18.4 minutes). Although drug users and non-users reported similar sleep duration (about 7.4 hours), drug users showed poorer subjective sleep quality and habitual sleep efficiency. They reported more sleep disturbance and need for sleep medications, more daytime dysfunction and poorer subjective sleep quality compared with nondrug users. The total PSQI score positively correlated with the duration of drug use (rp = 0.164, p < 0.001). We also found a link between sleep problems and cigarette smoking, alcohol drinking, and duration of drug use.

CONCLUSIONS

Poor sleep quality is common among illicit drug dependent subjects. Long-term substance users had more sleep problems. Future research aiming at quantifying the benefits of treatment interventions should not neglect the influence of sleep problems. Gaining more insight into the impact of sleep quality on the addiction treatment could also help to target future intervention measures more effectively.

Association between personality traits and DSM-IV diagnosis of insomnia in peri- and postmenopausal women

OBJECTIVE

The aim of this study was to determine the role of personality factors in the development of DSM-IV insomnia coincident with perimenopause.

METHODS

Perimenopausal women (35 women with DSM-IV insomnia and 28 women with self-reported normal sleep) underwent clinical assessments and completed menopause-related questionnaires, the NEO Five Factor Inventory and the Structured Interview for DSM-IV Personality. Logistic regressions determined whether personality factors and hot flash-related interference were associated with an insomnia diagnosis concurrent with the menopausal transition.

RESULTS

Women with insomnia reported higher neuroticism, lower agreeableness, and lower conscientiousness than controls on the NEO Five Factor Inventory. Moreover, women with insomnia were more likely to meet DSM-IV criteria for cluster C personality disorders, particularly obsessive-compulsive personality disorder, on the Structured Interview for DSM-IV Personality. Women with insomnia were more likely to have had a past depressive episode and a history of severe premenstrual symptoms. Findings from regressions revealed that higher neuroticism and greater interference from hot flashes were associated with insomnia classification even after controlling for history of depression, suggesting that sensitivity to hot flashes and a greater degree of neuroticism are independent contributors toward establishing which women are most likely to have sleep problems during perimenopause.

CONCLUSIONS

Findings show the relevance of personality factors, particularly neuroticism and obsessive-compulsive personality, to a woman's experience of insomnia as she goes through the menopausal transition.

The impact of obesity and weight gain on development of sleep problems in a population-based sample

OBJECTIVES

The objective of this study was to investigate the role of obesity and weight gain in the development of sleep problems in a population-based cohort.

MATERIAL AND METHODS

A population-based sample of men (n = 1896, aged 40-79 years) and women (n = 5116, age ≥20 years) responded to questionnaires at baseline and follow-up after 10-13 years. Sleep problems were assessed through questions about difficulties initiating sleep (DIS), difficulties maintaining sleep (DMS), excessive daytime sleepiness (EDS), and insomnia. Body mass index (BMI) was calculated from self-reported weight and height at both baseline and follow-up, while confounding factors (physical activity, tobacco and alcohol use, somatic disease, and snoring) were based on responses at baseline.

RESULTS

Although overweight and obese subjects reported more sleep problems at baseline, there was no independent association between BMI level at baseline and development of new sleep problems. Subjects in the quartile with the highest rise in BMI with a weight gain exceeding 2.06 kg/m2 had a higher risk of developing DMS [adjusted odds ratio (OR) 1.58; 95% confidence interval (CI) 1.25-2.01), EDS (2.25; 1.65-3.06], and insomnia (2.78; 1.60-4.82). Weight gain was not associated with the development of DIS.

CONCLUSIONS

Weight gain is an independent risk factor for developing several sleep problems and daytime sleepiness. The presence of overweight and weight gain should be considered when treating patients with sleep problems.

Sleep disturbances in adults in a city of Sao Paulo state

OBJECTIVE

To analyze the occurrence of sleep-related disorders among adults from Presidente Prudente, Brazil, as well as to identify associations with behavioral, socio-demographic and nutritional status variables.

METHODS

After random selection of the sample, interviews were performed with 743 adults of both genders, living in Presidente Prudente, Brazil. Sleep-related disorders, demographic variables (sex, age, ethnicity and schooling), behavioral variables (leisure physical activity, alcohol consumption, and smoking) and nutritional status were analyzed by questionnaires.

RESULTS

The prevalence of sleep-related disorders was 46.7%, with 95% confidence interval (95%CI) 43.1 - 50.2. In the multivariate analysis, female sex, with odds ratio (OR) 1.74 (95%CI 1.26 - 2.40), schooling (OR = 0.49; 95%CI 0.28 - 0.82), overweight (OR = 1.99; 95%CI 1.39 - 2.85) and obesity (OR = 2.90; 95%CI 1.94 - 4.35) were associated with sleep-related disorders.

CONCLUSION

There is high occurrence of sleep-related disorders in this sample, which was associated with female sex, lower schooling, overweight and obesity.

Insomnia among community dwelling elderly in Alexandria, Egypt

BACKGROUND

Insomnia is a common problem in the elderly population. Poor sleep quality is associated with decreased memory and concentration, increased risk of falls, cognitive decline, and higher rate of mortality. Inadequate sleep hygiene such as irregular sleep schedules, use of stimulants, and daytime naps may predispose to insomnia.

AIM

The aim of this study was to determine the prevalence of insomnia among community dwelling elderly in Alexandria and to assess some of the risk factors and comorbid conditions related to insomnia.

PARTICIPANTS AND METHODS

This is a cross-sectional study conducted among 380 elderly people taken from different clubs in Alexandria using a predesigned structured interview questionnaire. Data on sociodemographic characteristics, medical history, and personal and sleeping habits were collected. The Insomnia Severity Index was used to assess insomnia and the Depression Anxiety Stress Scale was used to measure depression, anxiety, and stress.

RESULTS

One-third (33.4%) of the elderly suffered from insomnia. On logistic regression, the most independent factors that were significantly associated with insomnia were number of chronic diseases [odds ratio (OR)=7.25 for having ≥5 diseases], being female (OR=2.37), anxiety (OR=1.91), watching television in bed before sleeping (OR=1.90), depression (OR=1.74), nocturia (OR=1.13), and daily sunlight exposure (OR=0.57).

CONCLUSION AND RECOMMENDATIONS

Insomnia is a common problem among the elderly in Alexandria. Female sex, chronic diseases, mental health problems, and bad sleep hygiene practice increase the risk for insomnia. Improving knowledge among the elderly about the prevalence and risk factors of insomnia could help the development of effective public health prevention and intervention programs for better sleep quality.

Sleep disturbance, chronic stress, and depression in hospice nurses: testing the feasibility of an intervention

PURPOSE/OBJECTIVES

To test the feasibility of a cognitive-behavioral therapy for an insomnia (CBT-I) intervention in chronically bereaved hospice nurses.

DESIGN

Five-week descriptive correlational.

SETTING

Nonprofit hospice in central Texas.

SAMPLE

9 agency nurses providing direct patient and family care.

METHODS

Direct care nurses were invited to participate. Two intervention group sessions occurred at the hospice agency and included identification of dysfunctional thoughts and beliefs about sleep, stimulus control, sleep hygiene, and relaxation techniques to promote sleep. Measurements were taken at baseline and three and five weeks postintervention.

MAIN RESEARCH VARIABLES

Sleep quality, depressive symptoms, and narrative reflections on the impact of sleep quality on self-care.

FINDINGS

Participants reported moderate-to-severe sleep disturbances and moderate depressive symptoms. The CBT-I intervention was well accepted by the participants, and on-site delivery increased participation.

CONCLUSIONS

Additional longitudinal study is needed to investigate the effectiveness of CBT-I interventions to improve self-care among hospice nurses who are at high risk for compassion fatigue and, subsequently, leaving hospice care.

IMPLICATIONS FOR NURSING

Hospice nurses are exposed to chronic bereavement that can result in sleep disturbances, which can negatively affect every aspect of hospice nurses' lives. Cognitive-behavioral sleep interventions show promise in teaching hospice nurses how to care for themselves by getting quality sleep.

KNOWLEDGE TRANSLATION

Identifying the risks for sleep disturbances and depressive symptoms in hospice nurses will allow for effective, individualized interventions to help promote health and well-being. If hospice nurses achieve quality sleep, they may remain in the profession without suffering from chronic bereavement, which can result in compassion fatigue. A CBT-I intervention delivered at the agency and in a group format was feasible and acceptable by study participants.

Insomnia among patients with advanced disease during admission in a Palliative Care Unit: a prospective observational study on its frequency and association with psychological, physical and environmental factors

BACKGROUND

THE AIMS OF THIS STUDY WERE

1) to assess the frequency of insomnia among patients during admission in a Palliative Care Unit (PCU); 2) to study the association between emotional distress and insomnia, taking physical, environmental and other psychological factors into account.

METHODS

Prospective observational study including patients consecutively admitted to a PCU during eight months, excluding those with severe cognitive problems or too low performance status. Insomnia was assessed by asking a single question and by using the Sleep Disturbance Scale (SDS), and emotional distress using the Hospital Anxiety and Depression Scale (HADS). Physical, environmental and other psychological factors potentially interfering with sleep quality were evaluated. Association between insomnia and the factors evaluated was studied using univariate and multivariate regression analyses.

RESULTS

61 patients were included (mean age 71.5 years; 95% with oncological disease); 38 (62%) answered "yes" to the insomnia single question and 29 (47%) showed moderate to severe insomnia according to the SDS. 65% showed clinically significant emotional distress and 79% had nocturnal rumination. The physical symptoms most often mentioned as interfering with sleep quality were pain (69%) and dyspnoea (36%). 77% reported at least one environmental disturbance. In the univariate analysis, answering "yes" to the insomnia single question was significantly associated with higher HADS score, anxiety, nocturnal rumination, clear knowledge of the diagnosis, higher performance status and dyspnoea; moderate to severe insomnia was significantly associated with nocturnal rumination, higher performance status, environmental disturbances and daytime sleepiness. In the multivariate regression analysis, answering "yes" to the single question was associated with dyspnoea (OR 7.2 [1.65-31.27]; p = 0.009), nocturnal rumination (OR 5.5 [1.05-28.49]; p = 0.04) and higher performance status (OR 14.3 [1.62-125.43]; p = 0.017), and moderate to severe insomnia with nocturnal rumination (OR 5.6 [1.1-29.1]; p = 0.041), and inversely associated with daytime sleepiness (OR 0.25 [0.07-0.9]; p = 0.043).

CONCLUSIONS

Insomnia was highly frequent. Several physical, psychological and environmental factors seemed to influence insomnia. Within the multimodal management of insomnia, the assessment of nocturnal rumination may be of particular interest, irrespective of emotional distress. Further studies with larger sample sizes could confirm this result.

Sex differences in stress-related psychiatric disorders: neurobiological perspectives

Stress is associated with the onset and severity of several psychiatric disorders that occur more frequently in women than men, including posttraumatic stress disorder (PTSD) and depression. Patients with these disorders present with dysregulation of several stress response systems, including the neuroendocrine response to stress, corticolimbic responses to negatively valenced stimuli, and hyperarousal. Thus, sex differences within their underlying circuitry may explain sex biases in disease prevalence. This review describes clinical studies that identify sex differences within the activity of these circuits, as well as preclinical studies that demonstrate cellular and molecular sex differences in stress responses systems. These studies reveal sex differences from the molecular to the systems level that increase endocrine, emotional, and arousal responses to stress in females. Exploring these sex differences is critical because this research can reveal the neurobiological underpinnings of vulnerability to stress-related psychiatric disorders and guide the development of novel pharmacotherapies.

Stress and sleep reactivity: a prospective investigation of the stress-diathesis model of insomnia

STUDY OBJECTIVES

To prospectively assess sleep reactivity as a diathesis of insomnia, and to delineate the interaction between this diathesis and naturalistic stress in the development of insomnia among normal sleepers.

DESIGN

Longitudinal.

SETTING

Community-based.

PARTICIPANTS

2,316 adults from the Evolution of Pathways to Insomnia Cohort (EPIC) with no history of insomnia or depression (46.8 ± 13.2 y; 60% female).

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

Participants reported the number of stressful events they encountered at baseline (Time 1), as well as the level of cognitive intrusion they experienced in response to each stressor. Stressful events (OR = 1.13; P < 0.01) and stress-induced cognitive intrusion (OR = 1.61; P < 0.01) were significant predictors of risk for insomnia one year hence (Time 2). Intrusion mediated the effects of stressful events on risk for insomnia (P < 0.05). Trait sleep reactivity significantly increased risk for insomnia (OR = 1.78; P < 0.01). Further, sleep reactivity moderated the effects of stress-induced intrusion (P < 0.05), such that the risk for insomnia as a function of intrusion was significantly higher in individuals with high sleep reactivity. Trait sleep reactivity also constituted a significant risk for depression (OR = 1.67; P < 0.01) two years later (Time 3). Insomnia at Time 2 significantly mediated this effect (P < 0.05).

CONCLUSIONS

This study suggests that premorbid sleep reactivity is a significant risk factor for incident insomnia, and that it triggers insomnia by exacerbating the effects of stress-induced intrusion. Sleep reactivity is also a precipitant of depression, as mediated by insomnia. These findings support the stress-diathesis model of insomnia, while highlighting sleep reactivity as an important diathesis.

CITATION

Drake CL, Pillai V, Roth T. Stress and sleep reactivity: a prospective investigation of the stress-diathesis model of insomnia.

Unveiling the longitudinal association between short sleep duration and the incidence of obesity: the Penn State Cohort

OBJECTIVE

Several epidemiologic, longitudinal studies have reported that short sleep duration is a risk factor for the incidence of obesity. However, the vast majority of these studies used self-reported measures of sleep duration and did not examine the role of objective short sleep duration, subjective sleep disturbances and emotional stress.

DESIGN

Longitudinal, population-based study.

SUBJECTS

We studied a random sample of 815 non-obese adults from the Penn State Cohort in the sleep laboratory for one night using polysomnography (PSG) and followed them up for a mean of 7.5 years. Subjective and objective measures of sleep as well as emotional stress were obtained at baseline. Obesity was defined as a body mass index (BMI) ≥30 kg/ m(-2).

RESULTS

The incidence of obesity was 15% and it was significantly higher in women and in individuals who reported sleep disturbances, shorter sleep duration and higher emotional stress. Significant mediating effects showed that individuals with subjective sleep disturbances who developed obesity reported the shortest sleep duration and the highest emotional stress, and that subjective sleep disturbances and emotional stress were independent predictors of incident obesity. Further analyses revealed that the association between short sleep duration, subjective sleep disturbances and emotional stress with incident obesity was stronger in young and middle-age adults. Objective short sleep duration was not associated with a significantly increased risk of incident obesity.

CONCLUSION

Self-reported short sleep duration in non-obese individuals at risk of developing obesity is a surrogate marker of emotional stress and subjective sleep disturbances. Objective short sleep duration is not associated with a significant increased risk of incident obesity. The detection and treatment of sleep disturbances and emotional stress should become a target of our preventive strategies against obesity.

Predictors of adherence to a brief behavioral insomnia intervention: daily process analysis

Behavioral interventions for insomnia are effective in improving sleep, yet adherence is variable, and predictors of adherence have not been consistently replicated. The relationships between daily variations in state factors at the initiation of treatment and adherence have not been investigated. Using 2-week, self-report online logs, this study determined, among 53 college students with probable insomnia, the associations of pretreatment factors and daily factors during treatment on daily variations in adherence to one session of behavioral treatments for insomnia. These treatments included stimulus control therapy (SCT), sleep restriction therapy (SRT), and sleep hygiene (SH). Low self-efficacy was associated with poorer SCT and SH adherence. Participants with a "bed partner or pet" at least some of the time had better SCT adherence. Greater total sleep time and poorer sleep quality were associated with poor SCT and SRT adherence the following night. Greater sleep efficiency was related to greater next night SCT and SRT adherence. Alcohol consumption was related to poorer SRT and SH adherence the following night. Future studies should test the replicability of these findings. Adherence trials may want to test whether discouraging alcohol intake, enhancing treatment-related self-efficacy, and monitoring and providing feedback on sleep, early in treatment, affects adherence.