Daylength during pregnancy and shyness in children: results from northern and southern hemispheres.
An extreme degree of shyness in young children is a temperamental trait under modest genetic influence and characterized by distinct physiological profiles. Data from both the United States and New Zealand indicate that maternal exposure to short daylength during pregnancy, especially the midpoint of gestation, predicts an increased risk of subsequent shy behavior in children. Estimates of attributable risk indicate that approximately one-quarter of shyness prevalence can be linked to pregnancy during times of reduced daylength. This phenomenon might be mediated by changing concentrations of melatonin, serotonin, or other neurotransmitters or corticoids that are known to covary with seasonal variations in daylength.
Gortmaker
S L
SL
Department of Health and Social Behavior, Harvard School of Public Health, Boston, MA 02115, USA.
Kagan
J
J
Caspi
A
A
Silva
P A
PA
D002648:Child; D002675:Child, Preschool; D003431:Cross-Cultural Comparison; D005260:Female; D005865:Gestational Age; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008027:Light; D008137:Longitudinal Studies; D008297:Male; D009520:New Zealand; D010552:Personality Assessment; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D012307:Risk Factors; D012792:Shyness; D013694:Temperament; D014481:United States