Figure 1.

Model for the relationship between sleep and the immune system. In both flies and mammals, loss of sleep increases expression of nuclear factor κB (NF-κB) in mammals by increasing cytokine expression and in Drosophila through unknown mechanisms. The same immune/inflammation molecules are increased by infection. Cytokines or NF-κB, in turn, increase sleep in both systems, and increased sleep is associated with increased survival. IL-1, Interleukin 1; TNF-α, tumor necrosis factor α.