Growth hormone‐releasing hormone and interleukin‐1 in sleep regulation

Abstract

Growth hormone‐releasing hormone (GHRH) and interleukin‐1 (IL‐1) are putative endogenous sleep‐promoting substances. Evidence is reviewed showing that, 1 ) GHRH and IL‐1 promote non‐rapid eye movement sleep (NREMS); 2 ) if their production is enhanced, sleep is enhanced; and 3 ) if they are inhibited using either specific antibodies or peptide antagonists, sleep is reduced. Both are in the brain and both are also indirectly linked to sleep/wake cycles by various other evidence, e.g., growth hormone release and IL‐1 plasma levels vary in phase with sleep/wake cycles, Finally, their actions are directly linked to each other; e.g., IL‐1‐induced growth hormone release is mediated via GHRH. The evidence reviewed strongly implicates both GHRH and IL‐1 as key components in humoral sleep regulation. Humoral theories of sleep regulation are complementary to neural theories; both mechanisms affect each other and undoubtedly continuously interact to regulate sleep/wakc cycles.—Krueger, J. M., Obál, F., Jr. Growth hor mone‐releasing hormone and interleukin‐1 in sleep regulation. FASEB J. 7: 645‐652; 1993.