The Molecular-Genetic-Cellular Level -- The Ultradian Clock (~40 min) in Yeast (Saccharomyces cerevisiae) -- ENOX Proteins, Copper Hexahydrate-Based Ultradian Oscillators of the Cells' Biological Clock -- Self-Organized Intracellular Ultradian Rhythms Provide Direct Cell-Cell Communication -- Phosphorylation Dynamics in Mammalian Cells -- Is There a Mitochondrial Clock? -- Invertebrate Systems -- Ultradian and Circadian Rhythms: Experiments and Models -- Ultradian Lovesong Rhythms in Drosophila -- Mid-range Ultradian Rhythms in Drosophila and the Circadian Clock Problem -- Tidal Rhythms -- The Neuroendocrineal and Developmental Level -- Pulsatile Hormone Secretion: Mechanisms, Significance and Evaluation -- Ultradian Rhythms as the Dynamic Signature of Life -- The Mammalian Circadian Timekeeping System -- Ultradian and Circadian Rhythms in Human Experience -- Ultradian Cognitive Performance Rhythms During Sleep Deprivation -- High Frequency EEG and Its Relationship to Cognitive Function -- Total Sleep Deprivation and Cognitive Performance: The Case for Multiple Sources of Variance -- Open Questions on Mind, Genes, Consciousness, and Behavior: The Circadian and Ultradian Rhythms of Art, Beauty, and Truth in Creativity -- Genes, Sleep and Dreams -- Epilogue: A New Vision of Life. 5. 1. 1 Biological Rhythms and Clocks From an evolutionary perspective, the adaptation of an organism's behavior to its environment has depended on one of life's fundamental traits: biological rhythm generation. In virtually all light-sensitive organisms from cyanobacteria to humans, biological clocks adapt cyclic physiology to geophysical time with time-keeping properties in the circadian (24 h), ultradian (24 h) domains (Edmunds, 1988; Lloyd, 1998; Lloyd et al. , 2001; Lloyd and Murray, 2006; Lloyd, 2007; Pittendrigh, 1993; Sweeney and Hastings, 1960) By definition, all rhythms exhibit regular periodicities since they constitute a mechanism of timing. Timing exerted by oscillatory mechanisms are found throughout the biological world and their periods span a wide range from milliseconds, as in the action potential of n- rons and the myocytes, to the slow evolutionary changes that require thousands of generations. In this context, to understand the synchronization of a population of coupled oscillators is an important problem for the dynamics of physiology in living systems (Aon et al. , 2007a, b; Kuramoto, 1984; Strogatz, 2003; Winfree, 1967). Circadian rhythms, the most intensively studied, are devoted to measuring daily 24 h cycles. A variety of physiological processes in a wide range of eukaryotic organisms display circadian rhythmicity which is characterized by the following major properties (Anderson et al. , 1985; Edmunds, 1988): (i) stable, autonomous (self-sustaining) oscillations having a free-running period under constant envir- mental conditions of ca.