Later school start time is associated with better academic performance, sleep-wake rhythm characteristics, and eating behavior.

There are numerous studies which show that an early school start time has a negative impact on the sleep, well-being, and academic performance of students. There is not enough information on the association between school start time and eating disorders, however: the disruption of the circadian rhythm is known to be a risk factor for eating disorders. The aim of this study is to analyze the relationship between school start time (SST) and the sleep, well-being, academic performance, and eating behavior of children and adolescents. The study was conducted in April and May 2021 in two regions of Russia: the Komi Republic and Yekaterinburg. The online study involved the anonymous and voluntary participation of 6571 students in grades 6-11 (mean age: 14.5 ± 1.6 years, 60.1% female), who have morning classes. All participants were divided into three groups according to SST: 08:00 (<i>n</i> = 3661), 08:30 (<i>n</i> = 2020), and 09:00 (<i>n</i> = 890). Each participant of the study indicated their place of residence, SST, age, sex, height, weight, academic performance, and filled out the Munich Chronotype Questionnaire, the Zung Self-Rating Depression Scale, and the Yale Food Addiction Scale for Children. As a result of multiple regression analysis, it was shown that schoolchildren with SST of 09:00 wake up at a later time on school days (<i>B</i> = 0.432; <i>ΔR² </i>= 0.039), sleep more (<i>B</i> = 0.293; <i>ΔR² </i>= 0.004), have less pronounced social jetlag (<i>B</i> = -0.223; <i>ΔR² </i>= 0.005) and sleep loss (<i>B</i> = -0.292; <i>ΔR² </i>= 0.005), and higher academic performance (<i>B</i> = 0.113; <i>ΔR² </i>= 0.003) than schoolchildren with SST of 08:00. As a result of logistic regression analysis, it was found that the frequency of the detection of food addiction is ~30% lower in schoolchildren with SST of 09:00 (OR = 0.690; 95% CI = 0.485-0.981) than in their peers with SST of 08:00. Thus, an overly early SST in Russia has a negative impact on the sleep function, academic performance, and eating behavior of children and adolescents.