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April 1999

Cosleeping in Context: Sleep Practices and Problems in Young Children in Japan and the United States

Author Affiliations

From A Professional Corporation, Pacific Palisades, Calif (Dr Latz); the Department of Psychiatry, MetroHealth Medical Center, Case Western Reserve University School of Medicine, Cleveland, Ohio (Dr Wolf); and the Department of Pediatrics and Communicable Diseases and the Center for Human Growth and Development, University of Michigan, Ann Arbor (Dr Lozoff).

Arch Pediatr Adolesc Med. 1999;153(4):339-346. doi:10.1001/archpedi.153.4.339

Objective  To determine the relationship between cosleeping and sleep problems in cultures with very different sleep practices.

Design  Interview study.

Setting  Families in urban Japan and the United States identified through pediatric and other professional contacts.

Participants  Parents of healthy 6- to 48-month-old children (56 Japanese parents and 61 white US parents). All children had been breast-fed and lived in 2-parent, middle-class households.

Intervention  None

Main Outcome Measure  Sleep practices and sleep problems.

Results  More Japanese than US children coslept 3 or more times per week (59% vs 15%, P<.001). All cosleeping Japanese children regularly slept all night with their parents (vs 11% of US cosleepers, P<.001). Japanese and US children did not differ in part-night cosleeping (7% vs 13%, P = .37). Most Japanese children had adult company and body contact as they fell asleep, and fathers slept separately in 23% of families. A greater proportion of US children had regular bedtime struggles and night waking. Within the US sample, cosleeping was associated with more bedtime struggles (P<.001), night waking (P<.01), and overall stressful sleep problems (P<.01). In the Japanese sample, cosleeping was associated only with night waking (P<.05); however, the proportion of cosleeping Japanese children with frequent night waking was at the level reported for US children who slept alone (30% vs 23%, P = .47).

Conclusions  Cultural differences seem to influence the relationship between sleep practices and sleep problems. The experience of the Japanese families indicates that cosleeping per se is not associated with increased sleep problems in early childhood.