Abstract
A protocol of dietary and sleep/wake modifications was used in an attempt to phase-advance the circadian rhythms of several physiological variables. The protocol, originally developed by Ehret, Groh, and Meinert (1981) to preadjust travelers, was modified based on previous studies in our own lab and used in 25 healthy volunteers who were divided into chronotypes using the Morningness-Eveningness Questionnaire (MEQ) (Horne and Ostberg, 1976). Significant phase-advancement was seen in the temperature, systolic and diastolic blood pressure rhythms of evening types, and in the diastolic blood pressure rhythms of neutral types (p <.05). Effects seen in the other variables were neither as dramatic nor sustained.