Preschoolers who are sleepy during the day may have thinner subfoveal choroids compared with other children, new research published in Eye suggests. The team of investigators from China found children with clinically significant daytime sleepiness had a 13.05μm-thinner subfoveal choroid than kids without this sleep disorder.

The population-based, cross-sectional study enrolled 1,337 children between the ages of 60 and 72 months who were measured for subfoveal choroid thickness with SD-OCT. The team used the Chinese version of the Children’s Sleep Habits Questionnaire (CSHQ) to evaluate the participants. The CSHQ is one of the most commonly used surveys to screen sleep disorders among children four to 10 years old.

Daily activities were divided into five activities: outdoor activities, studying and reading for school assignments, reading for pleasure, using a computer or electronic device/playing video games and watching television.

The questionnaire included a total of 33 items that covered eight subscales: bedtime resistance, sleep onset delay, sleep duration, sleep anxiety, night wakings, parasomnias, sleep disordered breathing and daytime sleepiness. Parents were asked to rate the frequency of each item during a typical week on a three-point scale: “usually” (five to seven times per week), “sometimes” (two to four times per week) and “rarely” (zero to one time per week).

Participants with higher questionnaire results—which indicated a greater likelihood of sleep disorders—had thinner subfoveal choroids.

Out of the eight questionnaire subscale scores, only daytime sleepiness was negatively associated with subfoveal choroidal thickness. Specifically, the 364 children with clinically significant daytime sleepiness ( 27%) had significantly thinner subfoveal choroids than the other children (295.47μm vs. 308.52μm).

The study is unique since there are few investigations for choroidal thickness in preschool children younger than six years old, partially due to the difficulty in obtaining good OCT images from these young participants, the researchers suggest.

“Although this finding cannot prove a causative relationship, and the exact mechanism remains unknown, this study provides important information that daytime sleepiness, a common sleep disorder in modern society, is associated with altered ocular health in early childhood,” they wrote in their paper.