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January 1978

Biorhythms and Highway Crashes: Are They Related?

Author Affiliations

From the Department of Psychiatry and Behavioral Sciences (Drs Shaffer and Schmidt), Johns Hopkins University School of Medicine, the Baltimore City Hospitals (Dr Schmidt), the Maryland Medical-Legal Foundation, Inc, (Dr Shaffer and Mr Zlotowitz), and the Department of Pathology (Dr Fisher), University of Maryland School of Medicine, Baltimore.

Arch Gen Psychiatry. 1978;35(1):41-46. doi:10.1001/archpsyc.1978.01770250043003

• Biorhythm, a theory that purports to identify periods of increased individual susceptibility to accident or misfortune on the basis of recurring biological cycles, is currently enjoying world-wide popularity. In view of the implications of such a theory for both public health and safety, the present study was undertaken as an empirical test of its validity. Using data from 205 carefully investigated highway crashes (135 fatal; 70 nonfatal) in which the drivers were clearly at fault, the authors computed specific points in drivers' biorhythm cycles at which the accidents occurred. The observed frequencies of accidents occurring during so-called critical and minus periods were then compared with the frequencies to be expected on a chance basis alone. The results provided no evidence for a relationship between purported biorhythm cycles and accident likelihood.

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