Sleep as a mirror of developmental transitions in infancy: the case of crawling.

The associations between the onset of crawling and changes in sleep were examined in 28 infants who were followed from 5 to 11 months-of-age. Motor development and sleep (actigraphy) were assessed at 2- to 3-week intervals. Along with the overall improvement in sleep consolidation, periods of increased long wake episodes were also manifested; the rise in sleep disruption was temporally linked to crawling onset. The results of the study highlight the dynamic interrelations between domains of development, indicate that emerging motor skills may involve periods of disrupted sleep, and point to the moderating effect of age. Clarifying the factors involved in the interplay between developmental milestones and sleep remains a challenge for future research.