Chronobiologic aspects of blood cortisol levels and decay slopes following ethanol administration to adult human subjects.

When single oral doses of ethanol were given to human subjects at different circadian stages on different days, the blood cortisol levels displayed the expected circadian variation and were not significantly affected by the ethanol challenges. When the ethanol was administered repeatedly in a single 24-h experiment, the cortisol levels were variably elevated by these challenges, primarily in the afternoon hours; however, the circadian excursions did not appear to be blocked or markedly phase-shifted. The phase relationships of circadian blood cortisol levels and previously reported blood ethanol decay rates showed individual subject variation. They tended to occur in phase in two of five subjects and out of phase in the remaining three. It is concluded that cortisol clearance rates following ethanol doses are not independent of the circadian stage but are not necessarily synchronous with those for ethanol clearance.