The Uses of Melatonin

ack of sleep in children is a very difficult stress factor, especially in the case of children with disabilities.This can have severe detrimental effects on the family, particularly when already experiencing the stresses related to caring for a disabled child.Several approaches are available comprising both pharmacological and behavioural techniques.The exogenous use of melatonin, a hormone that is naturally found in the brain, has recently been gaining increasing attention in the treatment of many sleep disorders.1 The following review has been prepared exploring the current uses of melatonin in the paediatric population.A literature search in Medline and the Cochrane Library was conducted, utilising keywords such as ''melatonin'', ''children'', ''paediatrics'', ''uses'', ''sleep disorders'', ''EEG'', and ''epilepsy'', and produced 61 references that were useful in compiling this review. MELATONIN: A NATURAL HORMONEMelatonin is a natural hormone that is synthesised in the pineal gland in the brain.Described as the ''Dark Force'', 2 melatonin is heavily dependent on the circadian rhythm generated by the light/dark cycle.3 This endogenous clock in the human brain induces the secretion of melatonin at night, reaching maximum plasma concentrations at 3-4 am.When the retinas in the eyes detect light, melatonin synthesis is inhibited, leading to secretion only when the subject is in darkness.In humans, melatonin is first detected in babies of 3-6 months.Production increases to a maximum at 1-5 years, and begins to decrease around the beginning of puberty.4 Melatonin was first isolated in the 1960s by Lerner 5 who documented its hypnotic effects.Interest in this substance gradually began to increase, reaching a peak in the 1990s when melatonin was described as a ''miracle drug'' used to treat everything from jetlag to cancer as well as possessing an anti-aging effect.6 Although many of these claims were disputed, 7 its hypnotic effect when used for the treatment of sleep disorders has gained increasing credibility.8 Since then, the use of melatonin in children has become well documented, particularly in anecdotal reports and small studies.8-10 Particular uses emerged, specifically in treatment of sleep disorders 8 11-13 and epilepsy.4 14 Melatonin appeared to be especially targeted for blind children 10 15 and those with neurodevelopmental disabilities.12 16-18 Despite the extensive use and small studies surrounding melatonin, it remains an unlicensed medicine in the UK.There is little official information available regarding the safety and efficacy of melatonin use in adults or children.Although many small studies and case reports had noted some impact from melatonin, there were others that found it to be mostly ineffective.9 There has been no clear evidence of adverse events mentioned in any of the studies, although this does not rule out the possibility of rare or long term effects; particular concern was voiced regarding delayed puberty in pre-pubertal children.10 In addition, there is no universal agreement on the dose of melatonin that should be used, with studies reporting doses ranging from 0.3-500 mg of fast release melatonin.19 20 Many of these obscurities could be resolved by conducting randomised controlled trials for melatonin in children with neurodevelopmental disabilities and a wide range of sleep problems.Unfortunately, it has been shown that obtaining sponsorship for a randomised controlled trial (RCT) on melatonin is very difficult 21 considering the nature of this product, its over the counter status in some countries, and the age group being tested. USES OF MELATONIN Sleep disordersBedtime struggling and night awakenings have been known to affect about 20% of the general paediatric population.12 These disturbances could be a result of many causes such as pain, gastro- oesophageal reflux, excessive noise, illness, seizures, and emotional and other endogenous or environmental factors 13 Many times, sleep disorders are caused by circadian disturbances, whereby the sleep-wake rhythm is unsynchronised, leading to sporadic sleeping patterns.Often such disorders are associated with neurodevelopmental disabilities, epilepsy, and visual disturbances.22 When attempting to treat sleeplessness in children, particularly with neurodeve- lopmental disorders, the first step is to obtain an accurate sleep history documenting the child's ep74 www.archdischild.