“…This knowledge has facilitated translational breakthroughs, exemplified by personalized chronotherapy, for example, in which the timing of pharmaceutical administration is aligned to the patient’s circadian peak of receptivity to treatment (Giacchetti et al, 2006; Lévi et al, 2010). Whereas ultradian variation also provides clinically relevant information (Hompes et al, 1992; Sturis et al, 1992) and has long been suggested to be central to mammalian physiology (Brandenberger et al, 1987; Lloyd, 1992; Miyata et al, 2016; Veldhuis et al, 2008), there is no single accepted systems-level framework to unify the study of ultradian rhythms (URs) at the organismal level (Bashan et al, 2012; Bourguignon and Storch, 2017; Prendergast and Zucker, 2016). Because of the absence of a unifying framework, as well as the technical challenges of measuring endocrine systems at ultradian timescales, circadian studies outnumber ultradian studies nearly 32:1 (Landgraf et al, 2014; Prendergast and Zucker, 2016).…”