On the basis of a literature search, it can be concluded that very little research has been conducted concerning the functioning of the pineal gland and the levels of melatonin secretions in children who exhibit abnormal development. In normally developing children, no circadian rhythm in melatonin production is observed in the first three months of life. From the fourth month, the levels of nocturnal melatonin secretions steadily increase until reaching a peak at age three to five.

During the following 10-12 years, the levels gradually decrease, with a more rapid decrease at puberty [Arendt, 1995; Nowak and Zawilska, 1996]. Research on the role played by melatonin in children has principally focused on adolescents and the years of puberty [Kitay, 1954; Attanasio, 1983; Cavallo, 1992, 1993].

The level of melatonin secretions in depressed children have been found by some researchers to be lower than normal [Cavallo et al., 1987]. These findings, however, were not confirmed by other researchers [Shaffi et al., 1990]. Analyses of levels of melatonin metabolites excreted in urine in Downs syndrome children were also inconclusive [Reiter et al., 1996]. Melatonin has been used to control seizures in children [Champney et al., 1995; Axt, 1996; Molina-Carballo, 1997]. Sleep disorders in children have been treated with melatonin [Jan, 1994; Axt, 1996].