Rhythms and periodicity in health and disease.

Biorhythms longer than the circadian that influence reactions of people and characterizes some diseases have not received much medical attention. The lay press describes cycles of 23, 28 and 33 days said to regulate moods, intellectual ability and efficiency, respectively. Whether or not three overlapping cycles actually regulate three different vague reactions may be questioned. Of interest, however, are rhythms of similar tempo which control mensis, cyclic changes in male hormones and a number of periodic diseases. Although reports of more than 2500 cases of periodic diseases have been published, physicians generally are skeptical on the subject. Incorrect diagnosis leads to unnecessary testing, surgical exploration and medication.