Evaluating Model Fit

Major depressive disorder (MDD) is a debilitating disease that is characterized by depressed mood, diminished interests, impaired cognitive function and vegetative symptoms, such as disturbed sleep or appetite. MDD occurs about twice as often in women than it does in men and affects one in six adults in their lifetime. The aetiology of MDD is multifactorial and its heritability is estimated to be approximately 35%. In addition, environmental factors, such as sexual, physical or emotional abuse during childhood, are strongly associated with the risk of developing MDD. No established mechanism can explain all aspects of the disease. However, MDD is associated with alterations in regional brain volumes, particularly the hippocampus, and with functional changes in brain circuits, such as the cognitive control network and the affective-salience network. Furthermore, disturbances in the main neurobiological stress-responsive systems, including the hypothalamic-pituitary-adrenal axis and the immune system, occur in MDD. Management primarily comprises psychotherapy and pharmacological treatment. For treatment-resistant patients who have not responded to several augmentation or combination treatment attempts, electroconvulsive therapy is the treatment with the best empirical evidence. In this Primer, we provide an overview of the current evidence of MDD, including its epidemiology, aetiology, pathophysiology, diagnosis and treatment.

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Major depressive disorder

Objective: The recent obesity epidemic has been accompanied by a parallel growth in chronic sleep deprivation. Physiologic studies suggest sleep deprivation may influence weight through effects on appetite, physical activity, and/or thermoregulation. This work reviews the literature regarding short sleep duration as an independent risk factor for obesity and weight gain.

Short sleep duration and weight gain : a systematic review

This review summarizes the brain mechanisms controlling sleep and wakefulness. Wakefulness promoting systems cause low-voltage, fast activity in the electroencephalogram (EEG). Multiple interacting neurotransmitter systems in the brain stem, hypothalamus, and basal forebrain converge onto common effector systems in the thalamus and cortex. Sleep results from the inhibition of wake-promoting systems by homeostatic sleep factors such as adenosine and nitric oxide and GABAergic neurons in the preoptic area of the hypothalamus, resulting in large-amplitude, slow EEG oscillations. Local, activity-dependent factors modulate the amplitude and frequency of cortical slow oscillations. Non-rapid-eye-movement (NREM) sleep results in conservation of brain energy and facilitates memory consolidation through the modulation of synaptic weights. Rapid-eye-movement (REM) sleep results from the interaction of brain stem cholinergic, aminergic, and GABAergic neurons which control the activity of glutamatergic reticular formation neurons leading to REM sleep phenomena such as muscle atonia, REMs, dreaming, and cortical activation. Strong activation of limbic regions during REM sleep suggests a role in regulation of emotion. Genetic studies suggest that brain mechanisms controlling waking and NREM sleep are strongly conserved throughout evolution, underscoring their enormous importance for brain function. Sleep disruption interferes with the normal restorative functions of NREM and REM sleep, resulting in disruptions of breathing and cardiovascular function, changes in emotional reactivity, and cognitive impairments in attention, memory, and decision making.

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Control of Sleep and Wakefulness

This meta-analysis reviewed 126 published empirical articles over the past 50 years describing associations between marital relationship quality and physical health in more than 72,000 individuals. Health outcomes included clinical endpoints (objective assessments of function, disease severity, and mortality; subjective health assessments) and surrogate endpoints (biological markers that substitute for clinical endpoints, such as blood pressure). Biological mediators included cardiovascular reactivity and hypothalamic-pituitary-adrenal axis activity. Greater marital quality was related to better health, with mean effect sizes from r = .07 to .21, including lower risk of mortality (r = .11) and lower cardiovascular reactivity during marital conflict (r = -.13), but not daily cortisol slopes or cortisol reactivity during conflict. The small effect sizes were similar in magnitude to previously found associations between health behaviors (e.g., diet) and health outcomes. Effect sizes for a small subset of clinical outcomes were susceptible to publication bias. In some studies, effect sizes remained significant after accounting for confounds such as age and socioeconomic status. Studies with a higher proportion of women in the sample demonstrated larger effect sizes, but we found little evidence for gender differences in studies that explicitly tested gender moderation, with the exception of surrogate endpoint studies. Our conclusions are limited by small numbers of studies for specific health outcomes, unexplained heterogeneity, and designs that limit causal inferences. These findings highlight the need to explicitly test affective, health behavior, and biological mechanisms in future research, and focus on moderating factors that may alter the relationship between marital quality and health.

/pdf/marital-quality-and-health-a-meta-analytic-review-3j1hmcj5lz.pdf

Marital quality and health: A meta-analytic review.

Aerobic exercise improves self-reported sleep and quality of life in older adults with insomnia

Sleep duration has been linked to obesity and there is also an emerging literature in animals demonstrating a relationship between the timing of feeding and weight regulation. However, there is a paucity of research evaluating timing of sleep and feeding on weight regulation in humans. The goal of this study was to evaluate the role of sleep timing in dietary patterns and BMI. Participants included 52 (25 females) volunteers who completed 7 days of wrist actigraphy and food logs. Fifty-six percent were "normal sleepers" (midpoint of <5:30 AM) and 44% were "late sleepers" (midpoint of sleep ≥5:30 AM). Late sleepers had shorter sleep duration, later sleep onset and sleep offset and meal times. Late sleepers consumed more calories at dinner and after 8:00 PM, had higher fast food, full-calorie soda and lower fruit and vegetable consumption. Higher BMI was associated with shorter sleep duration, later sleep timing, caloric consumption after 8:00 PM, and fast food meals. In multivariate models, sleep timing was independently associated with calories consumed after 8:00 PM and fruit and vegetable consumption but did not predict BMI after controlling for sleep duration. Calories consumed after 8:00 PM predicted BMI after controlling for sleep timing and duration. These findings indicate that caloric intake after 8:00 PM may increase the risk of obesity, independent of sleep timing and duration. Future studies should investigate the biological and social mechanisms linking timing of sleep and feeding in order to develop novel time-based interventions for weight management.

https://onlinelibrary.wiley.com/doi/pdf/10.1038/oby.2011.100

Role of Sleep Timing in Caloric Intake and BMI

Circadian rhythms are near 24-h patterns of physiology and behaviour that are present independent of external cues including hormones, body temperature, mood, and sleep propensity. The term ‘ circadian misalignment ’ describes a variety of circumstances, such as inappropriately timed sleep and wake, misalignment of sleep/wake with feeding rhythms, or misaligned central and peripheral rhythms. The predominance of early research focused on misalignment of sleep to the biological night. However, discovery of clock genes and the presence of peripheral circadian oscillators have expanded the defi nitions of misalignment. Experimental studies conducted in animal models and humans have provided evidence of potential mechanisms that link misalignment to negative outcomes. These include dysregulation of feeding behaviours, changes in appetite stimulating hormones, glucose metabolism and mood. This review has two foci: (1) to describe how circadian misalignment has been defi ned and evaluated in laboratory and fi eld experiments, and (2) to describe evidence linking different types of circadian misalignment to increased risk for physical (cardiovascular disease, diabetes, obesity, cancer) and psychiatric (depression, bipolar, schizophrenia, attention defi cit) disorders. This review will describe the role of circadian misalignment as a risk factor for disease in the general population and in clinical populations, including circadian rhythm sleep disorders and psychiatric disorders.

Circadian misalignment and health

In spite of repeated calls for research and interventions to overcome individual and systemic barriers to psychological treatments, little is known about the nature of these barriers. To develop a measure of perceived barriers to psychological treatment (PBPT), items derived from 260 participants were administered to 658 primary care patients. Exploratory factor analysis on half the sample resulted in 8 factors, which were supported by confirmatory factor analysis conducted on the other half. Associations generally supported the criterion validity of PBPT scales, with self-reported concurrent use of psychotherapy and psychotherapy attendance in the year after PBPT administration. Depression was associated with greater endorsement of barriers. These findings suggest that the PBPT may be useful in assessing perceived barriers.

/pdf/perceived-barriers-to-psychological-treatments-and-their-4dlp4bbu01.pdf

Perceived barriers to psychological treatments and their relationship to depression

Background:Exercise improves sleep quality, mood, and quality of life among older adults with insomnia. The purpose of the study was to evaluate the daily bidirectional relationships between exerci...

Kelly Glazer Baron

Papers

Aerobic exercise improves self-reported sleep and quality of life in older adults with insomnia

Role of Sleep Timing in Caloric Intake and BMI

Circadian misalignment and health

Perceived barriers to psychological treatments and their relationship to depression

Exercise to improve sleep in insomnia: exploration of the bidirectional effects.