Study Objectives:The algorithms used to derive sleep variables from actigraphy were developed with adults. Because children change position during sleep more often than adults, algorithms may detect wakefulness when the child is actually sleeping (false negative). This study compares the validity of three algorithms for detecting sleep with actigraphy by comparing them to PSG in preschoolers. The putative infl uence of device location (wrist or ankle) is also examined. Methods: Twelve children aged 2 to 5 years simultaneously wore an actigraph on an ankle and a wrist (Actiwatch-L, MiniMitter/Respironics) during a night of PSG recording at home. Three algorithms were tested: one recommended for adults and two designed to decrease false negative detection of sleep in children. Results: Actigraphy generally showed good sensitivity (> 95%; PSG sleep detection) but low specifi city (± 50%; PSG wake detection). Intraclass correlations between PSG and actigraphy variables were strong (> 0.80) for sleep latency, sleep duration, and sleep effi ciency, but weak for number of awakenings (< 0.40). The two algorithms designed for children enhanced the validity of actigraphy in preschoolers and increased the proportion of actigraphyscored wake epochs scored that were also PSG-identifi ed as wake. Sleep variables derived from the ankle and wrist were not statistically different. Conclusion: Despite the weak detection of wakefulness, Actiwatch-L appears to be a useful instrument for assessing sleep in preschoolers when used with an adapted algorithm.
S C I E N T I F I C I N V E S T I G A T I O N SS leep is considered to be of paramount importance for brain development during the fi rst two years of life.1 In fact, children spend over half of their fi rst two years of life sleeping, with daily sleep duration decreasing from 14.5 to about 13 hours between 6 months and 2 years of age. 2,3 In the preschool years, daily sleep needs remain high, decreasing from 13 hours at 2 years to about 11 hours at 5 years.2-4 During infancy and childhood, frequent night awakenings or diffi culty falling asleep are among the most frequent developmental complaints. Studies estimate that from 10% to 75% of parents report that their children have sleep problems.5 Importantly, sleep problems tend to persist during childhood 6 and are associated with several adverse consequences for behavioral, cognitive, and emotional health. For example, it has been shown that sleep problems are associated with behavioral and emotional self-regulation problems.7 In fact, results suggest that when the sleep of preschoolers is insuffi cient or fragmented by wakefulness, they show more diffi culty inhibiting emotional responses and more frequent impulsive and aggressive behavior.8 Poor sleep quality also seems associated with obesity in preschool children.
9Studies further suggest that sleep problems, whether occurring in infancy 10 or at school age, 4,11 are associated with lower cognitive performance. In light of the prevalence and the serious consequences of pediatr...