Agreement rates between actigraphy, diary, and questionnaire for children's sleep patterns

OBJECTIVES: To describe sleep-wake patterns in kindergarten children by measures derived from questionnaire, diary, and actigraphy and to report rates of agreement between methods according to Bland and Altman. DESIGN: Cross-sectional study, data from 7 nights of actigraph recordings and sleep diary and from a questionnaire. SETTING: Children studied in their homes. PARTICIPANTS: Fifty children, aged 4 to 7 years. MAIN OUTCOME MEASURES: Sleep start, sleep end, assumed sleep, actual sleep time, and nocturnal wake time derived from different methods. RESULTS: Differences between actigraphy and diary were +/- 28 minutes for sleep start, +/- 24 minutes for sleep end, and +/- 32 minutes for assumed sleep, indicating satisfactory agreement between methods, whereas for actual sleep time and nocturnal wake time, agreement rates were not sufficient (+/- 106 minutes and +/- 55 minutes, respectively). Agreement rates between actigraphy and questionnaire as well as between diary and questionnaire were insufficient for all variables. Sex and age of children and socioeconomic status did not influence the differences between methods for all variables. CONCLUSIONS: Actigraphy and diary may be interchangeably used for the assessment of sleep start, sleep end, and assumed sleep but not for nocturnal wake times. The diary is a cost-effective and valid source of information about children's sleep-schedule times, while actigraphy may provide additional information about nocturnal wake times or may be used if parents are unable to report in detail. It is insufficient to collect information by a questionnaire or an interview asking about children's normal sleep patterns