The thalamus and insomnia.

The thalamus has been shown to play a primary role in the organization of the wake-sleep rhythm. This was confirmed by experimental findings in which athalamic cats displayed severe and persistent insomnia, and by clinical observations that thalamic degeneration, with selective or prevalent involvement of the anterior or dorsomedial nuclei, virtually abolishes the ability to generate electroencephalographic sleep patterns. Loss of sleep has been associated with autonomic (tachycardia, hyperthermia, tachypnea) and endocrine (increased plasma cortisol and catecholamine levels) activation. The clinical and experimental evidence suggests that degeneration of the anterior and dorsomedial thalamic nuclei (so-called "visceral thalamus") leads to permanent loss of autonomic and endocrine homeostasis and restorative body processes by relieving the hypothalamus of cortical inhibitory control.