The effect of light on the circulation

It has long been the practice in clinical work to apply measures for the lowering of blood pressure in hyperpiesis. The immediate purpose of this investigation is to examine the basis upon which phototherapy stands as a suitable agent for the lowering of blood pressure. The original application of light baths by Finsen is an expression of his belief in this form of therapy. Among the earliest quantitative observations are those of K. A. Hasselbalch and Jacobäus (1), who found that repeated exposures to the total radiations of the carbon are caused a fall in the blood pressure of about 10 per cent, in the medium-sized arteries. Bach (2) obtained similar results in 105 out of the 109 cases exposed to the quartz mercury- vapour lamp. These observers state that the lowering of blood pressure persisted for about a month. More recent observations by H. Königsfeld (3) corroborate these earlier findings, with the exception of a few individual variations.