Vulnerability to Stress-Related Sleep Disturbance and Insomnia: Investigating the Link with Comorbid Depressive Symptoms

Modeling longitudinal relationships between sleep disturbances and depressed mood in postpartum: A cross-lagged panel design

BACKGROUND

This short communication explores the interrelationships between depressed mood and sleep disturbances in one-year postpartum period.

METHODS

Utilizing data from the Interaction of Gene and Environment of Depression during PostPartum Cohort (IGEDEPP) involving 3310 French postpartum women, we employed a cross-lagged panel model (CLPM) to analyze the relationships between these two symptoms, across three time points (immediate postpartum [<1 week after delivery], early postpartum [<2 months after delivery], and late postpartum [2 months to 1 years after delivery]).

RESULTS

Depressed mood significantly influences sleep disturbances in late postpartum (β = 0.096, z-value = 7.4; p < 0.001) but not in early postpartum (p-value = 0.9). We found no cross-lagged influence of sleep disturbances on depressed mood in early (p = 0.066) or in late postpartum (p = 0.060). Moreover, depressed mood and sleep disturbances in immediate postpartum are predictive of similar symptoms in the two other postpartum periods (between each of the three periods, p = 0.006 and p < 0.001 for depressed mood, and p = 0.039 and p < 0.001 for sleep disturbances), thus demonstrating the stability of these symptoms over time.

LIMITATIONS

Although conducted with a prospectively assessed cohort, this study faces limitations due to potential methodological biases.

CONCLUSIONS

This study is a pioneering analysis of mutual causal interactions between depressed mood and sleep disturbances in the postpartum period, highlighting the need for vigilant monitoring, early detection, prevention of worsen outcomes and intervention on these symptoms.

Insomnia is more likely to persist than remit after a time of stress and uncertainty: a longitudinal cohort study examining trajectories and predictors of insomnia symptoms

STUDY OBJECTIVES

The study aimed to characterize insomnia symptom trajectories over 12 months during a time of stress and uncertainty, the coronavirus disease 2019 (COVID-19) pandemic. It also aimed to investigate sleep and psychological predictors of persistent insomnia symptoms.

METHODS

This longitudinal cohort study comprised 2069 participants with and without insomnia symptoms during the first year of the pandemic. Participants completed online surveys investigating sleep, insomnia, and mental health at four timepoints over 12 months (April 2020-May 2021). Additional trait-level cognitive/psychological questionnaires were administered at 3 months only.

RESULTS

Six distinct classes of insomnia symptoms emerged: (1) severe persistent insomnia symptoms (21.65%), (2) moderate persistent insomnia symptoms (32.62%), (3) persistent good sleep (32.82%), (4) severe insomnia symptoms at baseline but remitting over time (2.27%), (5) moderate insomnia symptoms at baseline but remitting over time (7.78%), and (6) good sleep at baseline but deteriorating into insomnia symptoms over time (2.85%). Persistent insomnia trajectories were predicted by high levels of sleep reactivity, sleep effort, pre-sleep cognitive arousal, and depressive symptoms at baseline. A combination of high sleep reactivity and sleep effort reduced the odds of insomnia remitting. Higher sleep reactivity also predicted the deterioration of good sleep into insomnia symptoms over 12 months. Lastly, intolerance of uncertainty emerged as the only trait-level cognitive/psychological predictor of insomnia trajectory classes.

CONCLUSIONS

Insomnia was more likely to persist than remit over the first year of the COVID-19 pandemic. Addressing sleep reactivity and sleep effort appears critical for reducing insomnia persistence rates after times of stress and uncertainty.

Sleep reactivity is associated with social anxiety and disordered-eating behaviors in college students

Objective: Investigate whether sleep reactivity was associated with social anxiety and disordered-eating behaviors in a college population. Participants: One hundred ninety-eight college-age men and women. Methods: Participants completed self-report measures of social anxiety, disordered-eating behaviors and sleep reactivity. Results: Sleep reactivity was associated with greater dietary restriction and purging, controlling for social anxiety but it was not associated with binge eating. Sleep reactivity was associated with elevated symptoms of social anxiety, controlling for disordered-eating behaviors. Conclusions: The results suggest that sleep reactivity represents a shared correlate of disordered-eating behaviors and social anxiety that may partially explain their co-occurrence. Interventions to help college students high in sleep reactivity effectively manage stress and regulate their sleep may aid in the prevention and treatment of social anxiety and disordered-eating behaviors.

Sleep disturbances and depression are bidirectionally associated among college student athletes across COVID-19 pandemic exposure classes

College athletes may be vulnerable to sleep disturbances and depression during the COVID-19 pandemic as a result of large shifts in social and athletic obligations. In a national sample of college athletes, we examined the associations between sleep disturbances and depression across two timepoints, using COVID-19 exposure as a moderator. Data were collected from 2098 NCAA Division I, II, and III college athletes during two timepoints, from April 10 to May 23, and from August 4 to September 15, 2020. First, a latent class analysis was conducted with five indicators of levels of COVID-19 exposure to determine different exposure profiles. Second, to examine the directionality of associations between sleep disturbance and depression, a cross-lagged panel model was added to the latent class membership structural equation model; this allowed for testing of moderation by COVID exposure class membership. Four highly homogeneous, well-separated classes of COVID-19 exposure were enumerated: Low Exposure (57%); Quarantine Only (21%); High Other, Low Self Exposure (14%); and High Exposure (8%). COVID-19 exposure class membership did not significantly moderate associations between sleep disturbances and depression. However, student athletes significantly differed in T2 depression by their COVID-19 exposure class membership. Depression and sleep disturbances were positively correlated at both timepoints (r _T1 = 0.39; r _T2 = 0.30). Additionally, cross-lagged associations were found such that T2 depression was associated with T1 sleep disturbances (β = 0.14) and vice versa (β = 0.11). These cross-lagged associations were not significantly affected by athletes' level of COVID-19 exposure during the beginning of the pandemic.

Daily reactivity to stress and sleep disturbances: unique risk factors for insomnia

STUDY OBJECTIVES

To naturalistically measure sleep disturbances following stress exposure (i.e. sleep reactivity) and stress responses following sleep disturbances (i.e. stress reactivity) at the daily level and prospectively examine these reactivity measures as individual risk factors for insomnia.

METHODS

The study assessed 392 nurses' sleep and stress for 14 days using daily diaries and actigraphy. Self-reported insomnia symptoms were assessed at the end of the 14 days, as well as 6 and 11 months later.

RESULTS

In multilevel modeling, while negative fixed effects indicated that shorter total sleep time (TST) and lower sleep efficiency led to greater stress and vice versa, significant random effects indicated individual variability in sleep reactivity and stress reactivity. In latent score change modeling, greater sleep reactivity (lower diary-determined sleep efficiency following greater stress) and greater stress reactivity (greater stress following shorter diary-determined TST) at baseline were associated with greater insomnia symptoms at 11 months (b = 10.34, p = .026; b = 7.83, p = .03). Sleep reactivity and stress reactivity also interacted to predict insomnia symptoms, such that sleep reactivity was significantly associated with insomnia symptoms for those with high (+1 SD) stress reactivity (b = 17.23, p = .001), but not for those with low (-1 SD) stress reactivity (b = 5.16, p = .315).

CONCLUSIONS

Baseline stress reactivity and sleep reactivity independently as well as jointly predict greater insomnia symptoms 11 months later. The findings delineate processes underlying the stress-diathesis model of insomnia and highlight the utility of longitudinal and naturalistic measures of sleep and stress reactivity.

The Role of Brain-Derived Neurotrophic Factor in Immune-Related Diseases: A Narrative Review

Brain-derived neurotrophic factor (BDNF) is a neurotrophin regulating synaptic plasticity, neuronal excitability, and nociception. It seems to be one of the key molecules in interactions between the central nervous system and immune-related diseases, i.e., diseases with an inflammatory background of unknown etiology, such as inflammatory bowel diseases or rheumatoid arthritis. Studies show that BDNF levels might change in the tissues and serum of patients during the course of these conditions, e.g., affecting cell survival and modulating pain severity and signaling pathways involving different neurotransmitters. Immune-related conditions often feature psychiatric comorbidities, such as sleep disorders (e.g., insomnia) and symptoms of depression/anxiety; BDNF may be related as well to them as it seems to exert an influence on sleep structure; studies also show that patients with psychiatric disorders have decreased BDNF levels, which increase after treatment. BDNF also has a vital role in nociception, particularly in chronic pain, hyperalgesia, and allodynia, participating in the formation of central hypersensitization. In this review, we summarize the current knowledge on BDNF's function in immune-related diseases, sleep, and pain. We also discuss how BDNF is affected by treatment and what consequences these changes might have beyond the nervous system.

The natural history of insomnia: high sleep reactivity interacts with greater life stress to predict the onset of acute insomnia

STUDY OBJECTIVES

Prior research suggests that some individuals have a predisposition to experience insomnia following acute stressors (i.e. sleep reactivity). The present study was a proof of concept and specifically aimed to provide additional empirical evidence that the link between stressful life events and the onset of acute insomnia is moderated by sleep reactivity.

METHODS

About 1,225 adults with a history of good sleep (Mage = 53.2 years, 68% female, 83% white) were recruited nationwide for an online study on sleep health. Participants completed surveys to assess sleep reactivity (baseline), sleep patterns (daily sleep diary), and stressful life events (weekly survey). All daily and weekly measures were completed for a one-year period. Sleep diary data were used to identify sleep initiation/maintenance difficulties, including whether they met criteria for acute insomnia at any point during the one-year interval.

RESULTS

Participants with high sleep reactivity compared to low sleep reactivity were at 76% increased odds of developing acute insomnia during the one-year interval. In general, greater weekly stressful life events were associated with greater insomnia during the subsequent week. Those participants with high sleep reactivity demonstrated a stronger relationship between weekly stressful life events and insomnia, such that they reported the greatest levels of insomnia following weeks where they experienced a greater number of stressful life events.

CONCLUSIONS

These results further support the sleep reactivity model of insomnia, and specifically, provide evidence that sleep reactivity predicts the incidence of acute insomnia in a sample of participants with no history of insomnia.

The cumulative effect of chronic stress and depressive symptoms affects heart rate in a working population

BACKGROUND

Chronic stress and depressive symptoms have both been linked to increased heart rate (HR) and reduced HR variability. However, up to date, it is not clear whether chronic stress, the mechanisms intrinsic to depression or a combination of both cause these alterations. Subclinical cases may help to answer these questions. In a healthy working population, we aimed to investigate whether the effect of chronic stress on HR circadian rhythm depends on the presence of depressive symptoms and whether chronic stress and depressive symptoms have differential effects on HR reactivity to an acute stressor.

METHODS

1,002 individuals of the SWEET study completed baseline questionnaires, including psychological information, and 5 days of electrocardiogram (ECG) measurements. Complete datasets were available for 516 individuals. In addition, a subset (n = 194) of these participants completed a stress task on a mobile device. Participants were grouped according to their scores for the Depression Anxiety Stress Scale (DASS) and Perceived Stress Scale (PSS). We explored the resulting groups for differences in HR circadian rhythm and stress reactivity using linear mixed effect models. Additionally, we explored the effect of stress and depressive symptoms on night-time HR variability [root mean square of successive differences (RMSSD)].

RESULTS

High and extreme stress alone did not alter HR circadian rhythm, apart from a limited increase in basal HR. Yet, if depressive symptoms were present, extreme chronic stress levels did lead to a blunted circadian rhythm and a lower basal HR. Furthermore, blunted stress reactivity was associated with depressive symptoms, but not chronic stress. Night-time RMSSD data was not influenced by chronic stress, depressive symptoms or their interaction.

CONCLUSION

The combination of stress and depressive symptoms, but not chronic stress by itself leads to a blunted HR circadian rhythm. Furthermore, blunted HR reactivity is associated with depressive symptoms and not chronic stress.

Heart Rate Variability, Sleep Quality, and Depression in the Context of Chronic Stress

BACKGROUND

Disrupted sleep quality is one of the proposed mechanisms through which chronic stress may lead to depression. However, there exist significant individual differences in sleep reactivity, which is the extent to which one experiences sleep disturbances in response to stress.

PURPOSE

The aim of the current study was to investigate whether low high-frequency heart rate variability (HRV), as a psychophysiological marker of poor emotional and physiological arousal regulation, predicts stress-related sleep disturbances associated with greater risk of depression symptoms.

METHODS

Using a chronic caregiving stress model, 125 mothers of adolescents with developmental disorders and 97 mothers of typically developing adolescents had their resting HRV and HRV reactivity recorded and completed a measure of depressive symptoms, as well as a 7 day sleep diary to assess their sleep quality. A moderated mediation model tested whether sleep quality mediated the association between chronic stress exposure and depressive symptoms and whether HRV moderated this mediation.

RESULTS

After controlling for participant age, body mass index, ethnicity, socioeconomic status, and employment status, poor sleep quality mediated the association between chronic stress and depressive symptoms. Resting HRV moderated this indirect effect such that individuals with lower HRV were more likely to report poorer sleep quality in the context of chronic stressor exposure, which, in turn, was related to greater depressive symptoms.

CONCLUSIONS

Lower HRV, a potential biomarker of increased sleep reactivity to stress, is associated with greater vulnerability to stress-related sleep disturbances, which, in turn, increases the risk for elevated depressive symptoms in response to chronic stress.

Sleep Reactivity and Depressive Symptoms Among Chinese Female Student Nurses: A Longitudinal Mediation Analysis

Previous cross-sectional studies have documented that sleep reactivity was associated with depressive symptoms, but the potential mechanisms underlying this relationship were understudied. Therefore, the present study with a longitudinal prospective design was to reveal the mediating roles of sleep disturbance and emotion regulation difficulties (ERD) between sleep reactivity and depressive symptoms. This study included 725 student nurses who were followed up periodically for 9 months, with an interval of three months. All participants completed questionnaires regarding sleep reactivity, sleep disturbance, ERD, and depressive symptoms. Adjusted analyses suggested that the direct effect of sleep reactivity on depressive symptoms was non-significant. The bootstrap procedure revealed two significant indirect effects: from sleep reactivity to depressive symptoms with sleep disturbance as a mediator and from sleep reactivity to depressive symptoms with sleep disturbance and ERD as sequential mediators. Therefore, sleep reactivity might be considered as an indicator of shiftwork adaptability in the evaluation of recruitment. Psychological interventions aimed at developing healthy sleep habits and emotion regulation skills may be helpful in decreasing the risk of depression.

A negative cognitive style is associated with greater insomnia and depression symptoms: The mediating role of sleep reactivity

Insomnia and depression are distinct clinical phenomena, yet they are highly comorbid. One potential explanation for the high comorbidity rates is the overlap in risk factors. Atypical responses to stress, for example, place individuals at greater risk for both insomnia and depression. The goal of the present study was to simultaneously assess vulnerability to stress-related sleep disturbance (sleep reactivity) and the tendency to make negative attributions about stressful events (negative cognitive style), and how they relate to insomnia and depression. Study participants included 224 undergraduate students recruited from a large, public university in the United States. Sleep reactivity and negative cognitive style were assessed using the Ford Insomnia Response to Stress Test (FIRST) and the Cognitive Style Questionnaire (CSQ), respectively. Insomnia symptoms were assessed using the Insomnia Severity Index (ISI), and depressive symptoms were measured using the Center for Epidemiologic Studies Depression Scale (CES-D). Sleep reactivity was independently associated with greater insomnia and depression symptoms. Additionally, a negative cognitive style was related to greater depressive symptoms, and this effect was partially mediated by sleep reactivity. The current findings suggest that sleep reactivity may contribute to the development of disorders beyond insomnia. These findings further support the use of an interdisciplinary approach to investigating etiological models, and more specifically, the further exploration of how multiple stress responses (in terms of cognitions, sleep, etc.) place individuals at greater risk for developing psychopathology.

Bedtime social media use, sleep, and affective wellbeing in young adults: an experience sampling study

BACKGROUND

Findings from primarily cross-sectional studies have linked more extensive social media use to poorer sleep and affective wellbeing among adolescents and young adults. This study examined bedtime social media use, sleep, and affective wellbeing, using an experience sampling methodology with the aim of establishing a day-to-day temporal link between the variables. The study hypothesized a positive association between increased bedtime social media use and lower affective wellbeing the following day, mediated by poorer sleep.

METHODS

Using a smartphone application, 101 undergraduate students (M_age  = 19.70 years, SD = 1.09 years), completed daily questionnaires assessing the previous night's bedtime social media use and sleep duration and satisfaction (one measurement per day, questionnaire sent at 08:00), and momentary affective wellbeing (five measurements per day, at randomly varying times between 08:00 and 22:00 on weekdays and 10:00 and 22:00 on weekends), for 14 consecutive days. Objective assessments of total sleep time and sleep efficiency were obtained via wrist-worn actigraphs. By means of separate multilevel models, it was tested whether increased bedtime social media use predicted poorer sleep the same night, whether poorer sleep was predictive of positive and negative affect the following day, and whether sleep mediated the relationship between social media use and affective wellbeing.

RESULTS

Increased bedtime social media use was not associated with poorer sleep the same night. Apart from subjective sleep satisfaction, no other sleep variable (i.e., subjective sleep duration, objective total sleep time and objective sleep efficiency) predicted positive or negative affect the following day.

CONCLUSIONS

This study found that bedtime social media use is not detrimental to the sleep and affective wellbeing of healthy young adults. However, it is possible that bedtime social media use may be harmful to the sleep of vulnerable individuals.

The Moderating Effect of Sleep Disturbance on the Association of Stress with Impulsivity and Depressed Mood

OBJECTIVE

This study was performed to investigate the associations of life event stress with impulsivity, anxiety, and depressed mood as a function of the presence of a sleep disturbance.

METHODS

In total, 214 participants (age 38.96±10.53 years; 111 females) completed self-report questionnaires, including the Life Experience Survey (LES), Pittsburgh Sleep Quality Index (PSQI), Barratt's Impulsivity Scale (BIS), Beck Anxiety Inventory (BAI), and Beck Depression Inventory (BDI). The presence of a sleep disturbance was defined as a PSQI score >5.

RESULTS

In total, 127 participants presented with a sleep disturbance (age 39.33±10.92 years; 64 females), whereas the remaining 87 did not (age 38.43±9.97 years; 47 females). Negative LES scores were significantly correlated with BIS (r=0.22, p=0.001), BAI (r=0.46, p< 0.001), and BDI (r=0.51, p<0.001) scores, and PSQI scores were significantly correlated with BAI (r=0.49, p<0.001) and BDI (r=0.60, p< 0.001) scores. Moderation analysis revealed statistically significant interactions between negative LES scores and the presence of a sleep disturbance on BIS (p=0.044) and BDI (p=0.014) but not on BAI (p=0.194) scores.

CONCLUSION

The findings of the present study suggest that life event stress has varying degrees of influence on mental health, especially impulsivity and depressed mood, depending on the presence or absence of a sleep disturbance.

Association of stress-related sleep disturbance with psychiatric symptoms among pregnant women

BACKGROUND

Physiological changes during pregnancy are often accompanied by reduced sleep quality, sleep disruptions, and insomnia. Studies conducted among men and non-pregnant women have documented psychiatric disorders as common comorbidities of insomnia and other sleep disorders. However, no previous study has examined the association between stress-related sleep disturbances and psychiatric disorders among pregnant women.

METHODS

This cross-sectional study included a total of 2051 pregnant women in Peru. The Spanish-language version of the Ford Insomnia Response to Stress Test (FIRST-S) was used to assess sleep disruptions due to stressful situations. Symptoms of antepartum depression, generalized anxiety disorder, and posttraumatic stress disorder (PTSD) were examined using the Patient Health Questionnaire-9, Generalized Anxiety Disorder Scale-7 and PTSD Checklist - Civilian Version, respectively. High risk for psychosis was assessed using the Prodromal Questionnaire. Multivariable logistic regression procedures were used to estimate adjusted odds ratios (ORs) and 95% confidence intervals (CI).

RESULTS

Stress-related sleep disturbance was reported by 33.2% of women. Of all women, 24.9% had antepartum depression, 32.2% had generalized anxiety disorder, 30.9% had PTSD, and 27.6% were assessed as having a high risk of psychosis. After adjusting for confounders, women with stress-related sleep disturbances were more likely to experience antepartum depression (OR = 2.74; 95%CI: 2.22-3.38), generalized anxiety disorder (OR = 2.48; 95%CI: 2.04-3.02), PTSD (OR = 2.36; 95%CI: 1.93-2.88), and high risk for psychosis (OR = 2.07; 95%CI: 1.69-2.54) as compared to women without stress-related sleep disturbances.

CONCLUSIONS

Stress-related sleep disturbances during pregnancy are associated with increased odds of psychiatric disorders. Inquiring about stress related sleep disturbances during antenatal care may be beneficial for identifying and caring for women at high risk of psychiatric disorders.

A Meta-Analytical Review of the Genetic and Environmental Correlations between Reading and Attention-Deficit Hyperactivity Disorder Symptoms and Reading and Math

According to the Multiple Deficit Model, comorbidity results when the genetic and environmental risk factors that increase the liability for a disorder are domain-general. In order to explore the role of domain-general etiological risk factors in the co-occurrence of learning-related difficulties, the current meta-analysis compiled 38 studies of third through ninth-grade children to estimate the average genetic, shared environmental, and nonshared environmental correlations between reading and attention-deficit/hyperactivity disorder (ADHD) symptoms, and reading and math, as well as their potential moderators. Results revealed average genetic, shared and nonshared environmental correlations between reading and ADHD symptoms of .42, .64, and .20, and reading and math of .71, .90, and .56, suggesting that reading and math may have more domain-general risk factors than reading and ADHD symptoms. A number of significant sources of heterogeneity were also found and discussed. These results have important implications for both intervention and classification of learning disabilities.

Parenting Stress, Sleep, and Psychological Adjustment in Parents of Infants and Toddlers With Congenital Heart Disease

Objective

Parents of children with chronic medical needs report increased parenting challenges, poor sleep, and maladjustment. The impact of parenting stress on both sleep and adjustment has yet to be evaluated for parents of infants and young children with congenital heart disease (CHD). We studied the relations among parenting stress, sleep, and adjustment in parents of infants and toddlers with CHD. We expected that sleep quality would mediate the relationship between parenting stress and adjustment.

Methods

Sixty-nine parents of infants and toddlers with CHD were evaluated on self-report measures of illness-related parenting stress (Pediatric Inventory for Parents), sleep (Pittsburgh Sleep Quality Index), and psychological adjustment (Brief Symptom Index-18).

Results

The parents of infants and toddlers with CHD reported elevated levels of parenting stress, sleep problems, and maladjustment. The positive relationship between parenting stress and parent maladjustment was mediated by sleep quality.

Conclusions

Findings suggest that parents of infants and toddlers with CHD report high parenting stress, poor sleep, and maladjustment. Analyses indicate the stress-adjustment relationship is mediated by quality of sleep. Given the multiple demands on parents of infants and children with CHD, it is important to attend to parents’ overall functioning and mental health. Our findings highlight targets for intervention to improve the well-being of parents of young children with CHD.

Stress-related sleep reactivity is associated with insomnia, psychopathology and suicidality in pregnant women: preliminary results

INTRODUCTION

Depression and anxiety symptoms are commonly experienced by women during pregnancy and may have negative consequences on mothers and newborns. Deterioration of sleep quality throughout pregnancy increases insomnia, which may lead to adverse outcomes including increased psychopathology in the perinatal period. Thus, identifying women at high risk of developing insomnia may have important clinical implications on maternal-fetal outcomes. Stress-related sleep reactivity is a well-established risk factor for future insomnia, depression, and anxiety in general adult samples. However, little is known of sleep reactivity and its relations to sleep and mood pathology in pregnancy. Therefore, we explored sleep reactivity in pregnant women and its relations to prenatal symptoms of insomnia, depression, anxiety, and suicidality.

METHOD

Sixty-two pregnant women (mean age 33.6 ± 3 years, 20.6 ± 0.6 weeks of pregnancy) were evaluated during their routine visit at the Gynecological Unit of the University of Pisa, Italy, using the Insomnia Severity Index (ISI) for insomnia symptoms, the Ford Insomnia Response to Stress Test for sleep reactivity (FIRST), Edinburgh Postnatal Depression Scale (EPDS) for depressive symptoms, and the Zung Self Rating Anxiety Scale (SAS) for anxiety symptoms. Item #10 of the EPDS was used to assess for suicidality. Differences in means between women with high vs low stress-related sleep reactivity were calculated using t-test or Mann-Whitney U/Wilcoxon test. Linear/multiple regression analyses have been performed to study associations between variables.

RESULTS

Pregnant women with high stress-related sleep reactivity, relative to those with low reactivity, reported greater symptoms of insomnia (t = 6.5, 0.004) as well as higher rates of depression (62.0% vs 6.1%, p < 0.001), anxiety (55.1% vs 15.1%, p = 0.030), and suicidality (17.2% vs 3.0%, p = 0.025). Multivariate models revealed sleep reactivity to correlate independently with symptoms of insomnia, depression, and anxiety, when controlling for comorbid symptoms.

CONCLUSIONS

In mid-pregnancy, women with high sleep reactivity report elevated symptoms of insomnia, depression, and anxiety, and are more likely to endorse suicidal ideation. As a prognostic marker of future insomnia and psychiatric illness, early detection of high prenatal sleep reactivity holds potential to prevent the development of sleep and mood pathology during pregnancy, thereby potentially improving maternal and child outcomes.

The impact of stress on sleep: Pathogenic sleep reactivity as a vulnerability to insomnia and circadian disorders

Sleep reactivity is the trait-like degree to which stress exposure disrupts sleep, resulting in difficulty falling and staying asleep. Individuals with highly reactive sleep systems experience drastic deterioration of sleep when stressed, whereas those with low sleep reactivity proceed largely unperturbed during stress. Research shows that genetics, familial history of insomnia, female gender and environmental stress influence how the sleep system responds to stress. Further work has identified neurobiological underpinnings for sleep reactivity involving disrupted cortical networks and dysregulation in the autonomic nervous system and hypothalamic-pituitary-adrenal axis. Sleep reactivity is most pathologically and clinically pertinent when in excess, such that high sleep reactivity predicts risk for future insomnia disorder, with early evidence suggesting high sleep reactivity corresponds to severe insomnia phenotypes (sleep onset insomnia and short sleep insomnia). High sleep reactivity is also linked to risk of shift-work disorder, depression and anxiety. Importantly, stress-related worry and rumination may exploit sensitive sleep systems, thereby augmenting the pathogenicity of sleep reactivity. With the development of cost-effective assessment of sleep reactivity, we can now identify individuals at risk of future insomnia, shift-work disorder and mental illness, thus identifying a target population for preventive intervention. Given that insomniacs with high sleep reactivity tend to present with severe insomnia phenotypes, patient sleep reactivity may inform triaging to different levels of treatment. Future research on sleep reactivity is needed to clarify its neurobiology, characterize its long-term prospective associations with insomnia and shift-work disorder phenotypes, and establish its prognostic value for mental illness and other non-sleep disorders.

Assessing Stress-Induced Sleep Reactivity in College Students: The European Portuguese Version of the Ford Insomnia Response to Stress Test (FIRST)

OBJECTIVE AND BACKGROUND

Over the past few years, the comprehensive models of insomnia have exhibited impressive developments. However, there is scarce knowledge on predisposing or vulnerability factors for insomnia. One of the most promising constructs to aid in filling this gap is stress-induced sleep reactivity assessed through self-report. Our aim was to study the psychometric properties of the European Portuguese version of the Ford Insomnia Response to Stress Test (FIRST).

PARTICIPANTS

We recruited a large sample of students attending medical school (N = 699).

METHODS

Several analyses were carried out such as internal consistency, construct validity, and discriminant groups' analysis.

RESULTS

It was observed that FIRST-PT shows good internal consistency (Cronbach´s alpha = .81) and validity indicators. Interestingly, and contrary to what was observed in the previously published studies on psychometric properties of the FIRST, it was observed that a two-factor solution (Factor I = rumination, Factor II = worry) was the most adequate one to explain the correlation matrix, accounting for approximately 44% of the total variance.

CONCLUSIONS

The FIRST-PT proved to be a useful and reliable tool to measure stress-induced sleep reactivity. However, these results should be replicated in other groups, particularly clinical samples, in order to verify the stability of its factorial dimension.

Genetic Pathways to Insomnia

This review summarizes current research on the genetics of insomnia, as genetic contributions are thought to be important for insomnia etiology. We begin by providing an overview of genetic methods (both quantitative and measured gene), followed by a discussion of the insomnia genetics literature with regard to each of the following common methodologies: twin and family studies, candidate gene studies, and genome-wide association studies (GWAS). Next, we summarize the most recent gene identification efforts (primarily GWAS results) and propose several potential mechanisms through which identified genes may contribute to the disorder. Finally, we discuss new genetic approaches and how these may prove useful for insomnia, proposing an agenda for future insomnia genetics research.

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.