Modest first night effect on sleep in healthy school-age children using home-based polysomnography

Jia Xu Toby Seah; Nicole A Nazareth; Tiffany B Koa; Ju Lynn Ong; June Chi-Yan Lo

doi:10.1016/j.sleh.2026.05.002

Modest first night effect on sleep in healthy school-age children using home-based polysomnography

Sleep Health. 2026 Jun 3:S2352-7218(26)00080-X. doi: 10.1016/j.sleh.2026.05.002. Online ahead of print.

Authors

Jia Xu Toby Seah¹, Nicole A Nazareth², Tiffany B Koa¹, Ju Lynn Ong², June Chi-Yan Lo³

Affiliations

¹ Centre for Sleep and Cognition, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; Human Potential Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
² Centre for Sleep and Cognition, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
³ Centre for Sleep and Cognition, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; Human Potential Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore. Electronic address: june.lo@nus.edu.sg.

PMID: 42236444
DOI: 10.1016/j.sleh.2026.05.002

Abstract

Objectives: This study aimed to quantify the first night effect in healthy school-age children by comparing sleep macro- and microstructure between 2 non-consecutive nights of home-based polysomnography.

Methods: The sample consisted of 41 Singaporean children (mean age ± SD = 9.77 ± 1.29 years; 22 males) with data from 2 unattended home polysomnography recordings separated by at least 1 week. During the PSG nights, they were instructed to follow their habitual school-night sleep-wake timing. Within-subject differences in sleep macro- and microarchitecture were assessed using paired-sample t tests.

Results: In the first night, children spent 15.97 minutes longer in bed (dz = 0.33, P = .04), with no difference in total sleep time (P = .87). Also, the first PSG night involved longer wake after sleep onset (10.63 ± 7.47 minutes, dz = 0.37, P = .02) and lower sleep efficiency (-2.28 ± 3.37%, dz: 0.38, P = .02). Rapid eye movement (REM) sleep latency was also delayed by 19.39 minutes in the first night (dz = 0.36, P = .03). Durations of sleep stages, N2 and N3 latencies, and mean and total power across delta to beta frequency bands did not differ between nights (ps > 0.11).

Conclusions: In healthy school-age children sleeping at home, the first night effect appears modest, with small increases in nocturnal awakenings and delays in REM sleep onset, while sleep microstructure seems unaltered. These findings suggest that a single night of at-home PSG may provide relatively reliable sleep estimates for this age group.

Keywords: First night effect; Polysomnography; School-age children; Sleep architecture; Sleep microstructure.