A study of nearly 1,000 Canadian twins found genes play an important role in how long they sleep at night as infants and toddlers, but that environmental factors are more influential for daytime naps.
The study, “Genetic and Environmental Influences on Daytime and Nighttime Sleep Duration in Early Childhood,” published in the June 2013 issue of Pediatrics (published online May 27), uses data collected for the Quebec Newborn Twin Study on infants born between 1995 and 1998 in the Montreal area.
Parents answered questions about their child’s sleeping habits at ages 6, 18, 30 and 48 months. Researchers analyzed the responses and compared the results between fraternal and identical twins to tease out which sleep habits were more influenced by genes, and which by environment. Results show that genes largely influenced how long children slept at night, particularly for the persistently short sleepers. However, children’s nighttime sleep duration at 18 months of age was also significantly influenced by environmental factors, which suggests that is a good time for parents to implement strategies to improve their child’s nighttime sleep habits. The analysis showed environmental factors, rather than genes, strongly influenced children’s daytime napping habits.
Additional studies are needed to determine which genes could be contributing to short-persistent nighttime sleep duration and what environmental factors are most important for daytime sleep in early childhood.