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Genetic and environmental influences on sleep quality, ability to settle, and crying duration in 2‐ and 5‐month‐old infants: A longitudinal twin study

Year: 2025

Type: article

Abstract: Background Sleep and behavioral regulation are both vital for early healthy development. Yet, little is known about the relative contribution of genetic and environmental factors to early sleep and regulatory behaviors, or how these etiological influences may change during the first months of life. Methods Genetic and environmental influences on sleep, settle, and crying behaviors at 2 and 5 months were examined in 998 twins, using a classical twin design. In addition, polygenic scores were derived for a range of sleep behaviors, as well as psychiatric and neurodevelopmental conditions. Results Genetic influences (A) explained a large part of the variation in duration of crying at both 2 and 5 months (A = 0.29–0.70) and in settle ability at 5 months (A = 0.51–0.67). Shared environment (C) primarily influenced number of wakeups per night at both ages (C = 0.61–0.90) and settle ability at 2 months (C = 0.36–0.65). Longitudinal analyses suggested modest shared genetic influence on settle ability in the daytime across the ages (24%), and non‐significant shared genetic estimates for ability to settle in the evening and at nighttime. There was moderate shared influence of shared environmental factors on number of wakeups per night (56%) and modest but significant shared genetic influence on crying duration in the evening and nighttime (17%–33%). Unique environmental effects were mostly specific to each age. Finally, autism polygenic score associated with longer crying duration in the evening at 2 months ( β = 0.16, p = .002). Conclusions Etiological influences tended to change from 2 to 5 months, reflecting a highly plastic period in infant brain development and in child‐environment interactions.

Source: JCPP Advances

DOI: 10.1002/jcv2.70023

Authors: Charlotte Viktorsson, Ashraf Yahia, Mark J. Taylor, Angelica Ronald, Kristiina Tammimies, Terje Falck‐Ytter

Institutions: Uppsala University, Karolinska University Hospital, Karolinska Institutet, University of Surrey

Language: English

Topic: Infant Health and Development

Subfield: Pharmacy

Field: Health Professions

Domain: Health Sciences

SDG: Good health and well-being

Open Access status: gold

Estimated APC paid: $2,705