Lower melatonin levels may affect infant mental capacity, study

This conclusion is interesting, given increasing research into melatonin - often marketed as a sleep disorder aid - which is approved for use as a dietary supplement in the US, while its legality in different EU states depends upon whether it is classified as a food (or supplement) or medicine.

For instance, melatonin supplements are available over-the-counter in the UK, because the EU-wide list of approved nutrients for use in food supplements under the Food Supplements Directive is not up to date for hormones such as melatonin (as well as enzymes, probiotics, fatty acids).

Melatonin's antioxidant activity​

The background to the current study is the fact, highlighted by the authors Ferber et al., that medically low-risk pre-term infants score lower results (5 to 10 points on average) on the Mental Development Index (MDI) of the Bayley Scales of Infant Development.

Reduced melatonin secretion can cause sub-optimal oxygenation of the frontal lobe, said the authors, thus compromising the development of cognitive capacities in the newborn infant; they added that melatonin is considered a “powerful and readily available”​ antioxidant and scavenger of free radicals.

Said Ferber et al.:“In light of the sympathetic control of melatonin production, the antioxidant effect of melatonin and its recent clinical use for treatment of respiratory distress syndrome, we asked if the development of melatonin production is a mediator of the autonomic system’s impact on mental development.”​

Methodology​

Given seasonal effects on melatonin production in early life, the 39 Israeli infants who completed this study were all born in winter (October to March), with babies exhibiting genetic anomalies, heart malformations, gastrointestinal disturbances and central nervous system abnormalities excluded.

Children and mothers from pre-term and term births were recruited 2 to 9 days after delivery for the study, with mothers ignorant of the research question. Pre-term born infants were exposed to bright, intensive care lighting for 24 hours (day and night) until hospital discharge, and then to natural cyclical day-night lighting at home for the rest of the study.

Term-born infants were exposed to bright lighting for 2 days after birth until discharge, and then to cyclical day-night lighting at home for the rest of the study. Within both groups, melatonin levels in urine were measured by researchers, after mothers collected nappies between 7am and 7pm at the (corrected) ages of 4, 6 and 9 months.

Delayed melatonin production​

Alongside melatonin levels, the researchers examined neurobehavioural activity upon the basis of the Assessment of Pre-term Infant Behaviour (APIB), which assesses involves presenting infants with increasingly demanding behavioural inputs in a graded sequence at varying distances.

Mental Development Index (MDI) tests were also conducted by psychologists in the infants’ homes, and - as per the APIB tests - results showed a significant difference between term and pre-term infants at 4, 6 and 9 months:

“Pre-term profiles are characterised by compromised autonomic and motor functioning, state organisation, self-regulation and attention capacities at 2 weeks corrected age, as well as by delayed melatonin production and slower mental development up to 9 months when compared with term infants," ​wrote Ferber et al.

“We suggest that melatonin may be an important specific component that contributes to the development of of mental capacities, independent of the clock and dependent on the autonomic functioning.”​

Source: The Journal of Pediatrics, Melatonin and Mental Capacities in Newborn Infants ​(Article in Press)

Authors: Ferber, S.G, Als, H., McAnulty,G, Peretz, G., Zisapel, N.