Sleep deprivation is a major health problem in modern society. Deprivation of rapid eye movement (REM) sleep is particularly damaging to cognition and to spatial memory; however, the mechanisms that mediate these deteriorations in function are not known. We explored the possibility that REM sleep deprivation may provoke major changes in the immune system by inducing inflammation. Rats were subjected to 72 h of REM sleep deprivation, and the plasma levels of proinflammatory cytokines (IL-1, IL-1beta, IL-6, IL-17A, and TNF-alpha), an anti-inflammatory cytokine (IL-10), the inflammatory markers homocysteine, corticosterone, and hyperthermia were measured immediately after the deprivation period, and 7 days later. The results indicate that REM sleep deprivation induced an inflammatory response. The levels of the proinflammatory cytokines and markers were significantly elevated in sleep-deprived rats as compared to control rats. After 7 days of recovery, the levels of some markers, including hyperthermia, remained higher in sleep-deprived rats versus the control animals. IL-17A appears to play a pivotal role in coordinating the inflammation. These data shed new light on the mechanism of sleep deprivation-induced inflammation.