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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. [ABSTRACT FROM AUTHOR]

Objectives: Acute laboratory Stressors elicit elevations in serum levels of interleukin-6 (IL-6) and C-reactive protein (CRP). Chronic Stressors, such as family dementia caregiving, promote a state of chronic low-grade elevation in circulating inflammatory markers. The recurrent daily Stressors associated with chronic stress may lead to repeated and sustained activation of the physiological stress systems. The present study evaluated the possibility that greater exposure and reactivity to daily Stressors fueled increased levels of circulating inflammatory markers among family dementia caregivers, compared with noncaregiving controls. Methods: This cross-sectional study included 53 caregivers and 77 noncaregiving controls. A semistructured interview assessed the occurrence of daily Stressors in the past 24 h. A blood sample provided data on two inflammatory markers, C-reactive protein (CRP) and interleukin-6 (IL-6). Results: Caregivers were more likely to experience multiple Stressors in the past 24 h than noncaregiving controls. The occurrence of multiple daily Stressors was associated with greater serum IL-6 and CRP levels. The greater occurrence of daily Stressors in the past 24 h partially mediated the relationship between dementia caregiving and CRP levels. Conclusion: These results suggest that the cumulative effect of daily Stressors promotes elevations in inflammatory markers. Greater exposure to daily Stressors may be a psychobiological mechanism leading to elevations in CRP levels among family dementia caregivers. [ABSTRACT FROM AUTHOR]

Aging is associated with a natural dysregulation in immune functioning which may be amplified when it occurs in the context of chronic stress. Family dementia caregiving provides an excellent model to study the impact of chronic stress on immune functioning among older individuals. Empirical data suggest that the stress of caregiving dysregulates multiple components of innate and adaptive immunity. Elderly caregivers have poorer responses to vaccines, impaired control of latent viruses, exaggerated production of inflammatory mediators and accelerated cellular aging, compared to noncaregiving older adults. The chronic stress-induced immune dysregulation observed among older caregivers appears to be of sufficient magnitude to impact health. Furthermore, evidence suggests that chronic stress leads to premature aging of the immune system. Copyright © 2008 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]