Sleep disruption and motor development: Does pulling-to-stand impacts sleep–wake regulation?

• An intensive longitudinal design showed that sleep–wake regulation improves overtime but also encumbers set-backs.
• The association between sleep disruption and motor development was examined using actigraphy and observations.
• The new skill to pull-to-stand marked a period of an increase in night-waking, but only in early achievers of the milestone.
• How sleep and development are interrelated, and the significance of age in their coupling, call for further research.

During the second half of the 1st year, periods of increased sleep disruption have been documented alongside overall improvement in sleep–wake regulation. The objective of the present research was to test if pulling-to-stand (PTS), a milestone typically achieved during the latter part of the 1st year, co-occurs with a period of disrupted sleep. In a longitudinal design, 20 healthy infants were followed-up, from 7 to 11–12 months, at 3-week intervals. Each measurement consisted of filmed motor observations and sleep recordings (actigraphy), both conducted at home. It was found that among early achievers of PTS (by 8 months), the milestone was time-linked to a period of disrupted sleep. The results point to the significance of timing in the interplay between domains of development, and highlight the importance of considering both chronological and developmental metrics in studying changes in sleep–wake regulation.