A study of diurnal variation in circulating eosinophils especially with reference to sleep in healthy individuals.

It is well accepted from studies on adrenal cortical activity that stressful performance results in hypersecretion sometimes followed by hyposecretion. This physiological mainfestation has been called the "adaptation syndrome" (1). Along this line, two investigations were made to demonstrate the special diurnal rhythm in adrenal cortical activity of healthy men; in one of them 17-ketosteroid output in urine was followed throughout the day and night (2), and in the other circulating lymphocyte changes were seen in a successive period of 24hours. On the other hand, evidence was obtained that eosinopenia shows a good response to cortisone, a synthetic sugar-active 11-oxygenated corticosteroid which is known as an important product of adrenal cortex (4). Furthermore, Thorn Test based on the eosinophil change has been applied in many hospitals (5). So it was thought worth-while to show the evidence of diurnal changes in the number of circulating eosinophils which is intimately related to the activity of the sympathic-adrenal and the pituitary-adrenocortical system (5).