Normative values for sleep parameters in pre-schoolers using actigraphy.

OBJECTIVE: There are currently no reference values for actigraphy-measured sleep length and fragmentation in preschool children. We created standardized parameters using a community sample. METHODS: Ninety-seven 2-to-6-year-old children (56 boys) wore an actigraph on their non-dominant wrist for seven days. The data was extracted and scored, calculating total sleep time, sleep latency, sleep efficiency, fragmentation index, circadian rhythm length, cosine peak and light/dark ratio. Subjects were divided into groups of 2-3-year-olds, 4-5-year-olds and 6-year-olds. Means and standard deviations were calculated, and reference values were created using the 2.5th and the 97.5th percentiles. RESULTS: Reference intervals were 7 h 23 min-9 h 47 min for 24-hour total sleep time, 0.2-48.4 min for sleep latency, 69-87% for sleep efficiency, 23-53% for fragmentation index, 23 h 39 min-24 h 24 min for circadian rhythm length, 12:37-15:53 for the timing of the cosine peak, and 1.14-5.63 for the light-dark ratio. With increasing age, daily sleep time, sleep latency, sleep fragmentation, and napping decreased. CONCLUSIONS: We were able to create previously non-established reference values, including trends with increasing age, on actigraphy-assessed sleep in preschool children. SIGNIFICANCE: Sleep disorders in young children are easier to evaluate against normative data.