Culturally regulated effects on the early development of diurnal sleep and HPA-activity

Date of Completion

January 2006


Psychology, Developmental




Building on the Developmental Niche framework, the role of culture as a mediator for the development of pre- and early post-natal development of diurnal sleep rhythms and diurnal HPA-activity was investigated in two contrasting sites, the Netherlands and the US. There is little empirical research on culturally regulated diversity in normative bio-behavioral rhythms. The development of sleep-wake cycles is important because they constitute fundamental biological rhythms on which other daily rhythms are superimposed and they may reflect brain development. The ontological origins of sleep-wake cycles are poorly known, and much of the knowledge is derived from clinical, animal, or mono-cultural (mostly US) work. The maturing of sleep-wake cycles includes less of total sleep, a concentration of sleep in to longer sleep bouts, and greater synchronization of the patterning of sleep with the 24 hour night and day cycle. Previous findings (Super et al., 1996) suggest a cultural difference in the development of patterning in behavioral sleep and cortisol. Animal work suggests Zeitgebers, or predictable factors in the environment, are important for entraining diurnal rhythms. The main aim of the current dissertation was to examine the role of Zeitgebers within humanly constructed environments (physical and social) in regulating the development of diurnal rhythms. Overall, the results suggest that Dutch infants are exposed to Zeitgebers more regularly and develop mature rhythms earlier than American infants do. ^