Infant sleep consolidates rapidly during the first half year of life in the context of a dynamic, bidirectional exchange between infant characteristics and the caregiving environment. The current study examined the relationship between mothers' emotional availability (EA) at bedtime and infant temperament, and objectively assessing infant sleep development from one to six months, particularly focus on whether infant temperament moderated linkages between EA at bedtime and infant sleep development. The sample consisted of 72 mother–infant dyads, and the measures included actigraphy-assessed infant sleep at one and six months, observed maternal EA coded from bedtime videos at 3 and 6 months, and maternal reports of infant temperament at three and six months. The analysis showed significant positive effects of maternal EA at bedtime on developmental changes in infant sleep minutes. Additionally, infant temperamental surgency moderated the influence of EA at bedtime on the increase in infant sleep minutes. In other words, highly surgent infants whose mothers were emotionally available at bedtime showed a greater increase in their sleep time than other infants. The results are discussed in terms of the transactional model of infant sleep development.
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