AbstractsMedical & Health Science

Short sleep duration and poor sleep continuity have been related to adverse health outcomes. Sleep disturbances are more frequent among older people, who also experience a reduction in immune function (immunosenescence). This thesis tested the hypothesis that sleep disruption in old age contributes to immunosenescence. 93 healthy older subjects had their sleep recorded by actigraphy and immunological parameters were assessed. The data indicated that sleep continuity and duration in older adults does not influence innate immune function but was associated with changes in blood cell numbers, in particular an increase in the granulocyte:lymphocyte ratio. Differences in serum IL-4 and adiponectin were associated with long sleep duration and poor sleep continuity was also associated with raised serum cortisol. However, preliminary data obtained from a small pilot study of partial sleep deprivation in young and old adults did not show similar changes therefore causality was not confirmed. In vitro experiments were performed to evaluate whether adiponectin, whose levels change with age, affected neutrophil apoptosis and phagocytosis. Adiponectin extended lifespan of neutrophils and inhibited bacterial phagocytosis. The findings suggest that sleep dysregulation does not contribute to immunosenescence and in vitro studies add weight to the literature showing immunomodulatory roles for adiponectin.