Introduction A number of recent investigations have demonstrated that sensory deprivation can induce transient but severe cognitive, emotional, and behavioral changes in man.1,2Sensory deprivation has been utilized as a technique for producing stress of a nonspecific type, capable of eliciting specific behavioral and physiological responses under controlled conditions. The advent of recent bioassay and biochemical techniques has permitted the separation and analysis of the adrenal medullary hormones, epinephrine and norepinephrine, in man. Work by von Euler4established that epinephrine normally is secreted only by the adrenal medulla, while norepinephrine is secreted primarily by the endings of peripheral sympathetic nerves and secondarily by the adrenal medulla. Since the early work of Cannon5,6and his associates, it has been known that a variety of stress situations may produce an adrenal medullary hormonal response, as reflected in alterations of cardiovascular function.