Daytime nap controls toddlers' nighttime sleep.
Previous studies have demonstrated that afternoon naps can have a negative effect on subsequent nighttime sleep in children. These studies have mainly been based on sleep questionnaires completed by parents. To investigate the effect of napping on such aspects of sleep quality, we performed a study in which child activity and sleep levels were recorded using actigraphy. The parents were asked to attach actigraphy units to their child's waist by an adjustable elastic belt and complete a sleep diary for 7 consecutive days. 50 healthy young toddlers of approximately 1.5 years of age were recruited. There was a significant negative correlation between nap duration and both nighttime sleep duration and sleep onset time, suggesting that long nap sleep induces short nighttime sleep duration and late sleep onset time. We also found a significant negative correlation between nap timing and nighttime sleep duration and also a significant positive correlation between nap timing and sleep onset time, suggesting that naps in the late afternoon also lead to short nighttime sleep duration and late sleep onset. Our findings suggest that duration-controlled naps starting early in the afternoon can induce a longer nighttime sleep in full-term infants of approximately 1.5 years of age.
Department of Developmental Disorders, National Institute of Mental Health, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-higashi-cho, Kodaira, Tokyo 187-8553, Japan.|Department of Pediatrics, St. Luke's International Hospital, 9-1 Akashi-cho, Chuo-ku, Tokyo 104-8560, Japan.
Machiko
M
Nakagawa
Department of Developmental Disorders, National Institute of Mental Health, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-higashi-cho, Kodaira, Tokyo 187-8553, Japan.
Hidenobu
H
Ohta
Department of Pediatrics, St. Luke's International Hospital, 9-1 Akashi-cho, Chuo-ku, Tokyo 104-8560, Japan.
Yuko
Y
Nagaoki
Department of Pediatrics, St. Luke's International Hospital, 9-1 Akashi-cho, Chuo-ku, Tokyo 104-8560, Japan.
Rinshu
R
Shimabukuro
Faculty of Health Sciences, Hokkaido University, N12, W5, Kita-ku, Sapporo 060-0812, Japan.
Yoko
Y
Asaka
Faculty of Health Sciences, Hokkaido University, N12, W5, Kita-ku, Sapporo 060-0812, Japan.
Noriko
N
Takahashi
Maternity and Perinatal Care Center, Hokkaido University Hospital, N15, W7, Kita-ku, Sapporo 060-8638, Japan.
Takayo
T
Nakazawa
Maternity and Perinatal Care Center, Hokkaido University Hospital, N15, W7, Kita-ku, Sapporo 060-8638, Japan.
Yousuke
Y
Kaneshi
Maternity and Perinatal Care Center, Hokkaido University Hospital, N15, W7, Kita-ku, Sapporo 060-8638, Japan.
Keita
K
Morioka
Department of Pediatrics, Japanese Red Cross Medical Center, 4-1-22 Hiroo, Shibuya-ku, Tokyo 150-8935, Japan.
Yoshihisa
Y
Oishi
Department of Pediatrics, St. Luke's International Hospital, 9-1 Akashi-cho, Chuo-ku, Tokyo 104-8560, Japan.
Yuriko
Y
Azami
Department of Pediatrics, St. Luke's International Hospital, 9-1 Akashi-cho, Chuo-ku, Tokyo 104-8560, Japan.
Mari
M
Ikeuchi
Department of Pediatrics, St. Luke's International Hospital, 9-1 Akashi-cho, Chuo-ku, Tokyo 104-8560, Japan.
Mari
M
Takahashi
Department of Pediatrics, St. Luke's International Hospital, 9-1 Akashi-cho, Chuo-ku, Tokyo 104-8560, Japan.
Michio
M
Hirata
Department of Pediatrics, St. Luke's International Hospital, 9-1 Akashi-cho, Chuo-ku, Tokyo 104-8560, Japan.
Miwa
M
Ozawa
Maternity and Perinatal Care Center, Hokkaido University Hospital, N15, W7, Kita-ku, Sapporo 060-8638, Japan.
Kazutoshi
K
Cho
Department of Pediatrics, St. Luke's International Hospital, 9-1 Akashi-cho, Chuo-ku, Tokyo 104-8560, Japan.
Isao
I
Kusakawa
Department of Neonatology, Toho University Omori Medical Center, 6-11-1 Omori-nishi, Ota-ku, Tokyo 143-8541, Japan.
Hitoshi
H
Yoda
D056044:Actigraphy; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D012890:Sleep / Q000502:physiology*; D012892:Sleep Deprivation / Q000175:diagnosis*; D011795:Surveys and Questionnaires