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RESEARCH ACROSS THE GLOBE
NORWAY: Environmental influences on infant behavior and sleep development and the role of melatonin: preliminary data
There is an infant sleep study currently underway in Tromsø, Norway which, when concluded, will describe the development of infant melatonin levels in over 150 babies from birth to 6 months and will examine the effects of seasonal luminosity and nutrition on the development of melatonin levels and changes in sleep/wake cycles. Additionally the study will investigate the role of infant, maternal and care giving variables on infant melatonin levels and the development of infant sleep. A unique feature of this study is its location in a far northern region of Norway, characterized by extreme seasonal variation in daily luminosity. For two months in the winter, the sun never rises above the horizon and for two months in the summer it never sets below the horizon. For adults, the effects of changes in luminosity on melatonin and sleep are well documented. However, similar research with infants has not yet been conducted. When completed, this study will be the largest longitudinal study conducted on melatonin development in full term infants during the first six months of life. Furthermore, because of its location, the study will provide invaluable data regarding the effects of seasonal luminosity on infant development. Because of the strong seasonal component of this study, healthy newborns and their families were recruited in a window comprising three weeks before and after each of the equinoxes and solstices. All of the mothers had complication free pregnancies, while the babies in the study were all healthy and full term. The NBAS was used to examine newborn behavior at day 3 in the hospital and again in the home around 2 weeks (between day 10 - 18). The average age of the baby at the 2nd assessment was 13 days. Initial analysis showed there were seasonal differences in newborn behavior patterns, as measured on the Neonatal Behavioral Assessment Scale. The Lester et. al method of scoring was used for the ANOVA analysis, showing main effects for season, ranging from p<.05 to p<.001 level across clusters. The Motor and Autonomic clusters showed main effects for season on both the 3-day and the 13-day NBAS examination. On the Motor cluster of the NBAS at three days, the babies born in the Fall had the highest mean scores, followed by the Winter babies' scores, then the Spring babies' scores, while the scores of the babies born at Summer were lowest. On the second exam at 13 days, again significant seasonal differences were found in motor behavior: Winter babies had the highest scores on the Motor cluster, with the Fall babies next, followed by the Spring and Summer babies, in order. On the Autonomic cluster, both on the first and second exams, the Fall babies' mean scores were highest, followed by the Summer babies, and the Winter babies. Spring babies had the lowest mean scores on this cluster. On the second exam only there were additional clusters which showed main effects. In the Orientation cluster at the 2nd exam, the mean scores of the Fall babies were again highest followed by Winter, Summer and Spring. On the Reflex cluster, the Fall babies again showed the highest mean scores, followed by Summer babies, folowed by the scores of the Winter and Spring babies. In general, across the NBAS clusters, the mean scores of the babies born in the Fall, were consistently higher than the scores of the babies born in the other seasons, with the exception of the 2nd exam on the Motor cluster. The scores of the babies born in Winter and Summer are consistently lower and the scores of the babies born in Spring are lower still. Taking into account that these are all normal healthy babies, we are unsure how to characterize these findings. Once the infant melatonin analysis has been run in conjunction with the sleep data we may be able to speculate about the meaning of the seasonal variations which were found in newborn behavior. (References are available from the author) |
