SLEEP REGULATION: A BIDIRECTIONAL INTERACTION BETWEEN BRAIN AND THE ENDOCRINE SYSTEM

The purpose of this review is to summarize the current neuroendocrine knowledge base with particular emphasis on the bidirectional interaction on sleep regulation between the endocrine and the nervous system. These complex systems interact at multiple levels, both neuroendocrine and neuronal pathways are involved in the control of the humoral and cellular responses. Various hormones (peptides and steroids) participate in sleep regulation. A keyrole was shown for the reciprocal interaction between sleep-promoting growth hormone-releasing hormone (GHRH) and sleep-impairing corticotropin-releasing hormone (CRH). Besides of GHRH and CRH various other peptides and steroids participate in sleep regulation, many of them act via GABAergic mechanisms. In the light of neurobiological theories, primary insomnia may be conceptualised as the final common pathway of the interaction of a genetic vulnerability to an imbalance between arousing and sleep-inducing brain centres with perpetuating mechanisms such as maladaptive behaviours, learned sleep-preventing associations and cognitive factors.