Figure 2. A simplified, heuristic model of the interactions between central and peripheral components of the stress systems with sleep and REM sleep. CRH, corticotropin-releasing hormone; ACTH, corticotropin; LC/NE symp sys. locus ceruleus-norepinephrine/sympathetic system; AVP, arginine vasopressin; GH, growth hormone. A solid line denotes promotion/stimulation; a broken line denotes disturbance/inhibition.