Endocrine consequences of circadian rhythm disruption in early life

Circadian rhythms, primarily entrained through the light–dark cycle, play significant roles in the endocrine system. Fetal circadian rhythms develop through maternal rhythmic secretion of the hormones, melatonin and cortisol. This feto-maternal connection drives the development of the fetal circadian system until birth, to prepare the newborn for the postnatal environment. Conditions that affect maternal circadian rhythms (i.e. shift work and sleep disorders) can affect fetal circadian rhythmicity development, and thus the development of the offspring endocrine system. Furthermore, infants born preterm are hospitalised in neonatal intensive care units where constant light, loud noise and persistent handling disrupts infant sleep and circadian development. The consequences of circadian disruption include melatonin and glucocorticoid dysregulation, which can impact growth, development and other health outcomes.