Work

The association between small-for-gestational-age infant status and childhood wake-up time and bedtime: a nationwide cohort study in Japan

Year: 2026

Type: article

Abstract: Studies examining small-for-gestational-age (SGA) infants and sleep timing during childhood are scarce. We investigated the association between infant SGA status and sleep timing (wake-up time and bedtime) at age of 2.5 and 7 years using data from a Japanese birth cohort study conducted from 2001 ( n = 46,563). SGA was defined as birth weight below the 10th percentile for gestational age based on Japanese reference standards. The four sleep-timing outcomes were defined as wake-up time at or after 9:00 am or irregular and bedtime at or after 10:00 pm or irregular at 2.5 years, and wake-up time at or after 7:00 am or irregular and bedtime at or after 10:00 pm or irregular on school days at 7 years. These cut-off points were used as study-specific operational definitions based on the questionnaire response categories. Poisson regression with robust variance was used to estimate risk ratios (RRs) and 95% confidence intervals, adjusting for child and parental factors. In crude analyses, children born SGA had a slightly higher RR for bedtime at or after 10:00 pm or irregular at 2.5 years; however, this association was not significant after adjustment. No significant association was observed for the other outcomes. Sensitivity and stratified analyses yielded similar results.

Source: Scientific Reports

DOI: 10.1038/s41598-026-68765-3

Authors: Sumiyo Yasukawa, Naomi Matsumoto, Takashi Yorifuji

Institution: Okayama University

Language: English

Topic: Sleep and related disorders

Subfield: Experimental and Cognitive Psychology

Field: Psychology

Domain: Social Sciences

SDG: Good health and well-being

Open Access status: gold

Estimated APC paid: $2,690