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Abstract: Sleep is important for health; however, poor sleep is a growing problem in many Western societies, particularly among women. Alterations in immune function following poor sleep (defined by duration and disruption) may be linked to ill health. Not yet investigated are the possible effects on stress-induced mobilization of lymphocytes. As natural killer (NK) cells are particularly responsive to acute stress, the present study examined whether sleep period duration and percentage of time awake after sleep onset (WASO) the night before a laboratory stressor would predict reduced NK cell mobilization. Sleep was monitored by actigraphy in 39 healthy women. NK cell peripheral blood numbers were determined at baseline (post-20min rest), 4min into a Stroop task, immediately post-task and 30min after task completion. Participants with high WASO had significantly less NK cell mobilization to the stressor and failed to return to baseline levels after 30min compared to women with low WASO. No effects were found for sleep period duration. Findings raise the possibility that inadequate NK cell mobilization to, and poor recovery from acute stress may be one pathway by which sleep could impact health. [Copyright &y& Elsevier]

Abstract: Acute mental stress tests have helped to clarify the pathways through which psychosocial factors are linked to disease risk. This methodology is now being used to investigate potentially protective psychosocial factors. We investigated whether global self-esteem might buffer cardiovascular and inflammatory responses to acute stress. One hundred and one students completed the Rosenberg Self-Esteem Scale. Heart rate and heart rate variability (HRV) were recorded for 5min periods at baseline, during two mental stress tasks, (a speech and a color-word task) and 10, 25 and 40min into a recovery period. Plasma levels of tumor-necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interleukin-1 receptor antagonist (IL-1Ra) were assessed at baseline, immediately post-stress and after 45min recovery. Repeated measures analysis of variance demonstrated that heart rate levels were lower across all time points in those with high self-esteem, although heart rate reactivity to stress was not related to self-esteem. There were no differences in baseline HRV, TNF-α, IL-6 or IL-1Ra. Multiple linear regressions revealed that greater self-esteem was associated with a smaller reduction in heart rate variability during the speech task, but not the color-word task. Greater self-esteem was associated with smaller TNF-α and IL-1Ra responses immediately following acute stress and smaller IL-1Ra responses at 45min post-stress. In conclusion, global self-esteem is associated with lower heart rate and attenuated HRV and inflammatory responses to acute stress. These responses could be processes through which self-esteem protects against the development of disease. [Copyright &y& Elsevier]