title: Potentially harmful sleep habits of 3-year-old children in Japan.
abstract: To examine the sleep habits of 3-year-old children, we questioned guardians during a routine health examination for 3-year-old children at a public health center. According to the 1105 questionnaires analyzed, the proportion of children who fell asleep at 10 p.m. or later was 49.6%. The nocturnal sleep onset time was significantly correlated with the wake-up time in the morning and was significantly negatively correlated with the nocturnal sleep duration. The average daily total sleep duration (nocturnal sleep duration + nap duration) of regular nap-takers showed a significant negative correlation with the nocturnal sleep onset time. The average values for height, weight, and body mass index (BMI) were not correlated with the nocturnal sleep onset time. Children who went to sleep later got less sleep than those who went to sleep earlier. Because sleep debt has a harmful impact on older children and adults, late sleep onset may have adverse health consequences in young children.
authors.affiliation: Division of Human Ontogeny and Childhood Development, Graduate School, Tokyo Medical and Dental University, Japan. jkohyama.ped@tmd.ac.jp
authors.forename: Jun
authors.initials: J
authors.lastname: Kohyama
authors.forename: Toshihide
authors.initials: T
authors.lastname: Shiiki
authors.forename: Junko
authors.initials: J
authors.lastname: Ohinata-Sugimoto
authors.forename: Takeshi
authors.initials: T
authors.lastname: Hasegawa
mesh_terms: D002675:Child, Preschool; D005260:Female; D006184:Habits; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008019:Life Style; D008297:Male; D012307:Risk Factors; D012621:Seasons; D012890:Sleep / Q000502:physiology*; D012892:Sleep Deprivation / Q000453:epidemiology*; D011795:Surveys and Questionnaires; D013997:Time Factors