Effects of sleep and sleep loss on immunity and cytokines.

Sleep is hypothesized to be a restorative process that is important for the proper functioning of the immune system. Severity of disordered sleep in depressed- and alcoholic subjects correlates with declines in natural- and cellular immunity and is associated with alterations in the complex cytokine network. Sleep loss has a role in mediating these immune changes as experimentally induced partial night sleep deprivation replicates the kind of sleep loss found in clinical samples and induces a pattern of immune alterations similar to that found in depressed- and alcoholic patients. Despite evidence that sleep and sleep loss have effects on immune processes and nocturnal secretion of cytokines, the clinical significance of these immune changes is not known. Moreover, in view of basic evidence of a reciprocal interaction between sleep and cytokines, further research is needed to understand whether alterations in cytokines contribute to disordered sleep in patient populations. Copyright 2002 Elsevier Science (USA)