Sleep impacts the quality of life and is associated with cardiometabolic and neurocognitive outcomes. Little is known about sleep of preterm-born children at pre-school age. We, therefore, studied sleep and 24-hour rhythms of pre-school children born very-preterm compared to full-term children.

Prospective cohort study comparing sleep quality and quantity of children born very-preterm (gestational age (GA) <30 weeks) with full-term children at the (corrected) age of 3 years, using: 1) two parent-reported questionnaires (Brief Infant Sleep Questionnaire and The Munich Chronotype Questionnaire), and 2) at least 3-day days tri-axial wrist actigraphy combined with sleep diary. We performed regression analyses with adjustment for sex, (corrected) age and birthweight SD-score.

Ninety-seven very-preterm-born (median GA 27 + 5 (interquartile range 26 + 3;29 + 0)) and 92 full-term children (GA 39 + 3;38 + 4;40 + 4) were included. Sleep problems and other reported sleep parameters were not different between groups. As measured with actigraphy, sleep and 24-hour rhythm were similar between groups, except for very-preterm born children waking up 21 minutes (4;38) minutes later than full-term children (adjusted p=0.001).

Based on parent reports and actigraphy, very-preterm-born children sleep quite similar to full-term controls at the corrected age of three years. Reported sleep problems were not different between groups. Actigraphy data suggest that preterm born children may wake up later than children born full-term. Further studies are needed to explore how sleep relates to cardiometabolic and neurodevelopmental outcomes after preterm birth and whether early interventions are useful to optimize 24-h rhythm and sleep.