The time structure of living systems, which rules the autonomous temporal order of organisms as well as their coherence with the outer environment, has aroused considerable attention in biology and medicine since 1937, when a few European scientists gathered to establish this new field of research. This volume contains the Proceedings of the 2nd Annual Meeting of the European Society for Chronobiology, held in Marburg in 1986. It mirrors the great advances of chronobiology and chronomedicine in theory and practice up to the present. Distinguished scientists from European and other countries report on recent results in basic research and medical applications.