Association between salivary melatonin levels, sleep habits, and academic achievement in children: a pilot cross-sectional study

Sleep is crucial for brain development in children and melatonin is the main sleep-inducing hormone. However, the relationship between melatonin and academic achievement in children is not well understood. This study aimed to examine the associations between salivary melatonin levels, sleep habits, and academic achievement in elementary school children. The study comprised 63 children (26 boys and 37 girls) aged 9–12 years. Salivary melatonin levels were measured at two time points: morning (6:30 AM) and evening (9:30 PM). Sleep duration and social jetlag were assessed using self-report questionnaires. Teachers assessed the academic achievement (ranging from 21–63 points across seven school subjects). Morning salivary melatonin levels were negatively correlated with academic achievement (β = −0.312, p = 0.018), and the morning-to-evening salivary melatonin ratio was positively correlated with academic achievement (β = 0.291, p = 0.014). No correlation between evening salivary melatonin levels and academic achievement was observed. Sleep duration and social jetlag were also associated with academic achievement (p < 0.05 for all tests). Overall, morning salivary melatonin levels, morning-to-evening salivary melatonin ratios, sleep duration, and social jetlag were independently associated with academic achievement in elementary school children.