Criteria for nap identification in infants and young children using 24-h actigraphy and agreement with parental diary.

STUDY OBJECTIVES: The study aimed to determine if an automated algorithm, capable of batch scoring, could extract naps and other 24-h sleep-wake variables from actigraphy without the need for parental sleep diaries, which rely heavily on parental awareness of child sleep.

DESIGN: A cross-sectional design was used for the study.

SETTING: The study examined healthy infants/children in their home setting.

PARTICIPANTS: A total of 160 infants/children in five age groups (6 months, and 1, 2, 3½ and 5 years) participated in the study.

MEASUREMENTS AND RESULTS: Participants wore actigraphs for 5-7 days, and parents completed sleep diaries over 2 consecutive days. Three criteria were applied to find the minimum sleep time (20, 30 and 40 min) yielding the best nap agreement between diaries and actigraphy for nap/no-nap identification. Best agreements were 72.1% (20 min minimum), 78.4% (20 min), 91.0% (30 min) and 93.3% (30 min) for ages 6 months, 1, 2 and 3½ years, respectively. Kappa statistics classified nap-nap agreement as 'slight' for 6-month data but 'moderate' or 'almost perfect' for older age groups. The number of daytime naps extracted at each age group yielded no significant discrepancies between the methods. Diaries generally returned significantly earlier sleep onset, later sleep offset, longer sleep duration and fewer night wakings at 6 months and 1 and 2 years, but this was not significant at 3½ or 5 years of age.

CONCLUSIONS: Minimum age-specific sleep time thresholds are recommended to improve nap identification in actigraphy across infant and toddler age groups. The findings strengthen our confidence in the ability to collect actigraphy data in the absence of parental diaries, in 3½- and 5-year-olds, at least.