Actigraphy has been widely used in adults and children. In infants, validation of actigraphy has typically used a comparison with behaviorally determined sleep state classification rather than polysomnography (PSG). This study validated actigraphy against PSG for determining sleep and waking states in infants who were younger than 6 mo. Twenty-two healthy infants, 13 term and 9 preterm, were studied at three different matched postconceptional ages. Actigraph data were compared with PSG recordings in 1-min epochs. Agreement rate (AR), predictive value for sleep, predictive value for wake, sensitivity. and specificity were calculated and compared between activity thresholds and across ages with two-way ANOVA for repeated measures. Thirty-two validation studies were analyzed. Overall AR with PSG of 93.7 Ϯ 1.3 and 91.6 Ϯ 1.8 were obtained at 2-4 wk and 5-6 mo, respectively, at the low activity threshold setting, whereas the auto activity threshold gave the best agreement with PSG at 2-4 mo (AR 89.3 Ϯ 1.3%). Sensitivity values of 96.2 Ϯ 1.1% at 2-4 wk, 91.2 Ϯ 1.5% at 2-4 mo, and 94.0 Ϯ 1.9% were obtained at these same settings. There was no difference across ages in AR or sensitivity. PVW and specificity values were low in this study. We conclude that actigraphy is a valid method for monitoring sleep in infants who are younger than 6 mo. Newborn infants spend~70% of their time asleep, and maturation of sleep is one of the major developments that occur during the first year of life. Sleep-related problems are extremely common in the preschool years, affecting~30% of this age group (1). Indeed, sleep problems are the most common subject on which parents seek advice from health professionals in these preschool years. These problems can range from disrupted sleep patterns with frequent night awakenings to sleep deprivation. The long-term consequences of poor sleep patterns are known to be slow growth, behavioral problems, poor school performance, family disruption, and even child abuse (2). Most home-based studies on infant sleep patterns have relied in parental reports. However, studies that have used both subjective and objective measures have identified that parental reporting may underestimate night-time awakening (3). Actigraphy provides a useful tool that has advantages over other methods of sleep/wake assessment in that it provides a noninvasive, continuous assessment that can be used for prolonged periods of time in a variety of situations. The actigraph continuously records the occurrence of limb movements and then sums the number of movements for a given epoch length. Through the use of a specially developed algorithm, the motility levels can be computer scored into states of sleep or wake (4,5). The actigraph was first developed for use in adults; however, it has recently been used in children to distinguish between sleep and wakefulness and provides a reliable measure of sleep-wake organization and sleep quality (4). To date, only two studies have been conducted in infants to validate actigraphy against other...

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Summary Maturation of sleep/wake patterns is one of the most important physiological developments during the first year of life. In this study, we aimed to compare the use of actigraphy and parental sleep diaries (SD) for recording the development of sleep/wake patterns longitudinally in term infants in their own home environments over the first 12 months of life. Twenty healthy term infants (7F/13M) were studied for 3 days each month in their own homes over the first 12 months of life. Sleep/wake patterns were recorded using both SD and actigraphy (AW) (AW64, Mini Mitter Co. Inc., Sunriver, OR, USA). The development of sleep and wake was analysed over 24 h, during the day (08:00–20:00 hours) and during the night (20:00–08:00 hours). A total of 186 studies had complete data sets for both analysis methods. Overall, there was no difference between methods of measurement for determination of the total percentage of sleep or wake over 24 h, or for the total percentage of sleep or wake during the day. However, at night, AW scored less time asleep (73.3 ± 0.9%) and more time awake (26.7 ± 0.9%) compared with the SD (80.7 ± 1.04% and 19 ± 1.0%, respectively, P < 0.001). Mean percentage sleep during the day decreased from 51% at 1 month to 28% at 12 months with the 1‐month values being significantly higher than all other ages, while mean percentage sleep at night was only different between 1 month and 11 and 12 months. In conclusion actigraphy provides a useful tool for assessing the development infant sleep.