**1. Introduction**

In 1960, the chemical structure of melatonin was defined [1] since significant attention was attracted towards its use a few years earlier when the dermatologist Dr. Lerner and his colleagues observed that melatonin could cause the lightening of frog skin [2]. Melatonin has been found to affect a wide range of physiological processes such as sleep-wake cycles [3], circadian rhythms [4], sexual maturation [5], and aging [6].

Since then, exogenous melatonin has demonstrated a series of clinical effects [7, 8], and numerous clinical studies have been conducted, where improved sleep quality was documented following exogenous melatonin administration [9]. Recent studies demonstrated analgesic [10], anxiolytic [11], anti-inflammatory, and antioxidative effects [12] following administration of melatonin.
