Environmental impact on infant\u27s developing melatonin levels and sleep -wake cycles

The purpose of the study is to describe the development of infant melatonin levels form birth to six months, and to examine the effects of seasonal luminosity, and nutrition on the development of melatonin levels and changes in circadian sleep:wake cycles. Additionally the study will investigate the role of infant, maternal and care giving variables on the development of infant sleep. This longitudinal study will be conducted in Tromso, Norway, which, because of its far northern location (70° North), provides extremes in seasonal variations and light/dark cycles. 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. A total of 146 infants (ranging in age from birth to 6 months) and 146 mothers participated in the study. Four sampling periods occurred within a two week interval surrounding the Summer and Winter solstices and the Spring and All equinoxes. Results show that age is the primary developmental influence and seasonal light influences actual levels of development at three and six months of age