Is there a role for melatonin in the ICU?

Abstract

Summary: In the last decade, there have been significant developments in the understanding of the hormone melatonin in terms of its physiology, regulatory role and potential utility in various domains of clinical medicine. Melatonin's purported properties include, among others, regulation of mitochondrial function, anti-inflammatory, anti-oxidative and neuro-protective effects, sleep promotion and immune enhancement. As such, its role has been explored specifically in the critical care setting in terms of many of these properties. This review addresses the physiological basis for considering melatonin in the critical care setting as well as the current evidence pertaining to its potential utility.

Contributions of the study: This review examines and discusses the role of melatonin in the intensive care unit in terms of sleep, delirium and sepsis, both the physiology and as a therapy.

Keywords: delirium; intensive care unit; melatonin; sepsis; sleep.

Fig. 1

Action of light on the release of melatonin from the pineal gland. Dotted lines indicate release of inhibition of daytime light effect by darkness. Inh = inhibition

Figs 2A and B

Normal day and night (A) and changes in light, sleep and hormones in an ICU environment (B). Blue arrows indicate cortisol secretion and brown arrows indicate that of melatonin. Adapted from Daou et al.

Fig. 3

Pharmacokinetic profile of PRM (Circadin) compared with FR-melatonin 2 mg formulation. Adapted from Zisapel.