Sleep, settle, and crying behaviors at 2 months were not significantly associated with later developmental outcomes including language, autistic traits, or hyperactivity, though family income and corrected age were significant predictors of these early behaviors.
Key Findings
Results
Corrected age at assessment was significantly associated with number of wakeups per night and crying duration at 2 months.
Age (corrected) showed a significant negative association with number of wakeups per night (β = -0.212, p < 0.001)
Age (corrected) showed a significant negative association with crying duration (β = -0.154, p = 0.012)
Infants were assessed at a corrected age range of 27–99 days
The negative associations indicate that older infants within the sample woke up less frequently and cried for shorter durations
Results
Higher family income was significantly associated with shorter crying duration and shorter time to settle at 2 months.
Family income was a significant negative predictor of crying duration (β = -0.128, p = 0.018)
Family income was a significant negative predictor of time to settle (β = -0.147, p = 0.011)
The sample consisted of 362 infants assessed at 2 months of corrected age
Family income was not reported as significantly associated with number of wakeups per night
Results
Sleep, settle, and crying behaviors at 2 months were not significantly associated with parent-rated language comprehension or socio-communicative abilities at 14 months.
Outcomes measured at 14 months included parent-rated language comprehension and socio-communicative abilities
No statistically significant associations were found between any of the three early infant behaviors and these 14-month developmental measures
Sample size was 362 infants at baseline
Results
Sleep, settle, and crying behaviors at 2 months were not significantly associated with vocabulary, autistic traits, or hyperactivity at 24 months.
Outcomes measured at 24 months included vocabulary, autistic traits, and hyperactivity
No statistically significant associations were found between the 2-month behavioral measures and any of the 24-month developmental outcomes
The authors assessed multiple developmental domains to provide a broad picture of early childhood development
Conclusions
The authors conclude that sleep and settle behaviors in the first few months are not indicators of atypical development in early childhood in the general population.
The study assessed a general population sample of more than 350 infants
Three behaviors were assessed: number of wakeups per night, time to settle, and crying duration
The conclusion is specifically framed for the general population, not clinical populations
The authors note that while these behaviors 'can be challenging for caregivers,' they do not predict atypical development
What This Means
This research suggests that how much a 2-month-old baby wakes up at night, how long it takes them to settle, and how long they cry are not reliable indicators of developmental problems later in childhood. In a study of over 350 infants, researchers found no meaningful connection between these early sleep and crying behaviors and outcomes measured at 14 and 24 months, including language development, social communication skills, autistic traits, and hyperactivity.
The study did find that family income played a role in early infant behavior: babies from higher-income families tended to settle faster and cry for shorter durations. Additionally, older babies within the 2-month age window (which ranged from about 4 to 14 weeks of corrected age) tended to wake up less often and cry less, suggesting these behaviors naturally improve as infants mature in the first months of life.
This research suggests that parents and caregivers who are struggling with a baby who wakes frequently, takes a long time to settle, or cries a lot at around 2 months of age need not view these behaviors as warning signs for their child's future development. While such behaviors can be exhausting and stressful for families, the findings indicate they are a normal part of early infancy rather than early markers of developmental differences. The association with family income also points to the broader social and environmental context that may shape these early infant behaviors.
Viktorsson C, Hardiansyah I, Juslin A, Falck-Ytter T. (2026). How Are Sleep, Settle, and Crying Behaviors in 2-Month-Olds Related to Concurrent Family Factors and Later Development?. Developmental science. https://doi.org/10.1111/desc.70126