Children in Japan go to bed later and sleep for a shorter time than those in other countries around the world. A research group led by Assistant Professor Yoshiko Iwatani, Professor Ikuko Mohri, Professor Kuriko Shimono, and Specially Appointed Professor Masako Taniike of the United Graduate School of Child Development at Osaka University conducted eye tracking and electroencephalography to find effects of sleep habits in early childhood. They have found that the regular sleep habits in children aged around 1−2 years are associated with social development and brain function. The study was published in Sleep Medicine.
Multiple cohort studies have reported that short sleep duration in infancy was associated with developmental delays, hyperactivity, and cognitive decline at school age. However, these studies have revealed little about their neural basis.
To conduct an intervention study using "Nenne Navi," an interactive sleep awareness app developed by the research group, 83 pairs of infants aged 1 year, 6 months−2 years, and their parents were recruited. Among them, electroencephalograms and other data obtained from 72 pairs were analyzed. Moving forward, the research group will provide them with sleep guidance using Nenne Navi for 6 months and analyze how the data changes.
In the experiment, the screen was presented to a child held by his or her mother, and eye-tracking data and electroencephalograms were collected simultaneously when a human face and a geometric pattern were presented. In the eye-tracking measurement, a higher fixation percentage for the human face was considered to indicate a better social development level.
The eye tracking results showed that the fixation percentage for the human face was associated with the irregularity of sleep duration and bedtime, with a more irregular sleep pattern being associated with a lower fixation percentage for the human face. The electroencephalography analysis showed a negative correlation between synchronousness (strength of functional connectivity) in the right centro-parietal area and the total sleep duration. Overall, the irregularity in nighttime sleep duration was found to be associated with cognitive function, communication skills, and the fixation percentage for human faces.
Iwatani said, "We consider relevant elements, including the fixation percentage for human faces, socio-communicational development, and cognitive function, and a total of the elements as development. We found that the irregularity in nighttime sleep duration was associated with development and the degree of network connectivity between brain regions. Irregularities in the bedtime can disrupt the circadian rhythm. Irregular sleep habits in early childhood may cause growth delay because growth hormone is released during the first deep sleep, and also inadequate synaptic pruning because it occurs during sleep from about one year of age."
Journal Information
Publication: Sleep Medicine
Title: Regular sleep habits in toddlers are associated with social development and brain coherence
DOI: 10.1016/j.sleep.2024.10.018
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