Circadian Factors in Cluster Headache and Migraine

Abstract

Life on earth undergoes daily and seasonal rhythms of the solar cycle, and organisms have evolved behaviors and functions that respond to these predicted light-dark cycles. For most species, this is driven by a ∼24-hour rhythmic expression of a set of core clock genes/proteins, which can be entrained by extrinsic cues (also called zeitgebers), such as light and temperature.1 The clock proteins, in turn, regulate large networks of gene transcription to control circadian aspects of behavior (e.g., the sleep-wake cycle and feeding) and physiology (body temperature, blood pressure, hormone levels, and metabolism, etc). The mammalian clock is synchronized by the central pacemaker, the suprachiasmatic nucleus, of the hypothalamus. Integrating zeitgeber signals with neuroendocrine functions, the hypothalamus is essential for maintenance of homeostasis in the body.