Nocturnalism: an ethological theory of schizophrenia.

Schizophrenia is a human behavioral variant with a 1% phenotypic population frequency. As the major "mental illness" affecting human beings, it has defied all previous attempts to explain, predict or prevent its devastating clinical manifestations. In addition to unidentified nongenetic determinants, schizophrenia has genetic determinants in the absence of known specific neuropathological or biochemical correlates found in other entities conceptualized as genetic diseases. The fitness of schizophrenics is 0.7 of nonschizophrenics, and a 1% phenotypic population frequency is difficult to explain by mutation rate alone. An ethological theory of schizophrenia has been developed in which the genetic determinant is the nocturnal character of a postulated polymorphic trait termed when active. The nongenetic determinant is simply a sufficient intensity of specific frequencies of environmental light. According to the author's theory, a schizophrenic individual could be processing information while awake and exposed to light with a brain that is processing information as though he were asleep. The empirical data from which the theory is constructed are presented. THe theory is capable of explaining clinical schizophrenia within an ethological paradigm and makes several predictions, the most significant of which is that the absence of a sufficient intensity of specific frequencies of environmental light should ameliorate the major symptoms of clinical schizophrenia in individuals who possess its genetic determinant.