Pruritus that interferes with sleep is generally diagnosed as having an organic rather than a psychogenic basis. We compared the dermatologic and psychosocial parameters of 79 inpatients with psoriasis with moderate to severe pururitus with (W group; n = 46) and without (NW group; n = 33) wakenings from sleep in association with pruritus. At the time of the patients' admission, compared with the NW group the W group had more severe depressive psychopathologic features (p less than 0.05); were possibly alcoholic, according to behavioral criteria for alcoholism (p less than 0.005); reported a higher daily alcohol consumption (p less than 0.05); and had symptoms suggestive of periodic movements in sleep, or nocturnal myoclonus (p less than 0.05), a sleep physiologic disorder. The two groups did not differ with respect to pruritus severity or other dermatologic parameters at the time of admission or during inpatient treatment. Contrary to the generally accepted criterion for the organicity of pruritus, psychiatric and possibly sleep pathologic factors rather than primary dermatologic factors determined the wakenings from sleep as a result of pruritus.