Dissonance Between Parent-Selected Bedtimes and Young Children's Circadian Physiology Influences Nighttime Settling Difficulties

Abstract

Nighttime settling difficulties (i.e., bedtime resistance, sleep-onset delay) occur in about 25% of young children and are associated with attentional, behavioral, and emotional problems. We examined whether the timing of internal (endogenous) circadian melatonin phase (i.e., dim light melatonin onset; DLMO) and its relationship with parent-selected bedtimes were related to nighttime settling behaviors. Fourteen regularly napping preschoolers (8 females; 30-36 months) participated in a 6-day protocol (parent-report of nighttime settling, actigraphic assessment of sleep onset latency, evening salivary DLMO). Average DLMO clock time was 07:40 p.m. ± 00:48 minutes, occurring 29 minutes ± 32 minutes prior to bedtime (lights-out). Children with later DLMOs had longer sleep-onset latencies (r = .62) and poorer success in falling asleep (r = -.59). Children whose bedtimes were closer to their DLMO had longer sleep-onset latencies (r = .72) and increased bedtime resistance (r = -.54). We conclude that dissonance between parent-selected bedtimes and children's circadian physiology may contribute to the development of nighttime settling difficulties in early childhood.

Fig. 1

Evening melatonin profile for an individual child. Average bedtime during the 5 days prior to the salivary dim light melatonin onset (DLMO) assessment was 19:45 DLMO was 18:55 based on a 4 pg/mL threshold (dotted line). The bedtime (lights-out) phase angle of entrainment (interval between DLMO and parent-selected bedtime) was 50 minutes.

Fig. 2

Scatterplots of associations between circadian parameters and children's nighttime settling behaviors. Pearson correlations (*p < .05; **p < .01).