UC Berkeley

This dissertation explores in a series of four studies using a developmental perspective the nature of infant sleep and its relation to waking experiences. The first two studies suggest that the sleep disturbance, which is usually observed in the second half of the first year of life, is related to a major transition of the infants becoming effectively mobile through learning to crawl on hands and knees. The sleep disruptions are mainly explained by infants<&lsquo> heightened sensitivity to proximity of a caregiver as a result of the developmental shift initiated by the onset of crawling. Thus, the findings call for consideration of the <&ldquo>sleep disturbance<&rdquo> as a normal developmental phenomenon that should not be treated as a clinical problem but rather accepted with sensitivity from the parents. Based on the third study of the dissertation, however, parents often apply sleep-training techniques involving prolonged periods of infant crying during the same age period and sometimes as a reaction to the <&ldquo>sleep disturbance<&rdquo>. The sleep training is widely recommended together with solitary sleeping arrangement and the study findings demonstrate that the recommendations have a profound effect on parental decisions. However, the fourth study does not support the benefits of the recommendations. Based on the findings, sleep training is not associated with a better sleep. Instead, sleep-trained infants cry more at night and also have a worse mood in the morning. Night feeding, on the other hand, is associated with less crying both at night and during the day. Even though it is also associated with more time awake at night and less self<&ndash>soothing, it does not seem to affect the overall amount of sleep. In addition, the nature of <&ldquo>self<&ndash>soothing<&rdquo> as a self<&ndash>regulatory ability is questioned by the findings reported in the fourth chapter, since it does not appear to be related to the infant's daytime self-regulatory abilities. Though closer sleeping location and higher parental involvement at night are associated with more interrupted sleep, it is also related to better daytime behavioral outcomes in the infants. Together the findings of this dissertation suggest that the <&ldquo>sleep disturbance<&rdquo> in infancy might be normal for this phase of development, and recommendations given to parents should be carefully examined since those are affecting both infant and parents as one.