How Are Sleep, Settle, and Crying Behaviors in 2-Month-Olds Related to Concurrent Family Factors and Later Development?

Sleep, settle, and crying behaviors represent basic regulatory functions in early infancy, yet little is known about the factors that influence these behaviors and their relationship to later development in the general population. In this study, we assessed a sample of 362 infants, measuring parent-rated number of wakeups per night, time to settle, and crying duration at 2 months of corrected age (range 27-99 days), along with various background variables. We also measured several aspects of the infants' later development at 14 and 24 months. Age (corrected) at the first assessment showed a significant association with number of wakeups per night (β = -0.212, p < 0.001) and crying duration (β = -0.154, p = 0.012). Family income was a significant predictor of crying duration (β = -0.128, p = 0.018) and time to settle (β = -0.147, p = 0.011). Sleep, settle, and crying behaviors at 2 months were not significantly associated with parent-rated language comprehension or socio-communicative abilities at 14 months, nor with vocabulary, autistic traits, or hyperactivity at 24 months. While some sleep and settle behaviors in the first few months can be challenging for caregivers, our findings suggest that they are not indicators of atypical development in early childhood in the general population. SUMMARY: In a sample of more than 350 infants, we found that higher family income was associated with shorter time until settled and shorter crying duration at 2 months of age. Sleep, settle, and crying behaviors at 2 months did not show statistically significant associations with language development, hyperactivity, or autistic traits in toddlerhood.