Questionnaire survey on sleep habit of 3-year-old children in Asahikawa City

The present study surveyed the sleep habits of 3-year-old children in Asahikawa city using questionnaires completed by a parent during children's medical check-ups. Questionnaires were collected from the parents of 404 children (209 males, 195 females; mean age, 3.1 years) enrolled in this survey. Among these children, the mean bedtime was 9.6 PM with 145 children (36%) going to bed after 10 PM. On the other hand, the mean wake-up time was 7.5 AM, with 123 children (30%) waking up after 8 AM. The mean nocturnal sleep duration was 10.1 hours. Nocturnal sleep durations in children that went to bed after 10 PM were significantly shorter than in children who went to bed earlier (p < 0.01). Seventy-three percent of the children had a daily afternoon nap. Twelve percent of these children usually awoke from their nap after 5 PM, and the mean bedtime for these children was 10.1 PM. A late bedtime was significantly correlated with parental complaints such as short-temper and poor appetite (p < 0.05). Although parents were concerned about night-time sleep conditions, they were not concerned about the daytime conditions which regulate children's sleep-wake rhythm, such as daylight exposure, daytime activity, and naps. While 24% of parents had complains regarding their children's sleep, only 3% had consulted with a doctor. Similar to the previous reports, the present findings demonstrate that children in Asahikawa city go to bed late and have decreased sleep duration. Since the establishment of a normal sleep-wake rhythm is essential for both physical and mental development in children, it is necessary to educate parents regarding the importance of children's sleep.