Physical fitness and sleep-related problems among adolescents: findings from the EHDLA study

Physical fitness, particularly cardiorespiratory fitness, has been shown to positively impact sleep quality. However, the relation-ship between overall physical fitness and sleep-related problems in adolescents remains underexplored. Therefore, the aim ofthis study was to analyze the association between overall physical fitness and sleep-related problems in adolescents. This cross-sectional study included 812 adolescents (median age: 14 years [interquartile range = 12–17]; 54.9% girls) from the Eating Healthyand Daily Life Activities (EHDLA) data. Physical fitness was measured objectively using the Assessing the Levels of PHysicalActivity and fitness (ALPHA-Fit) battery for children and adolescents and a flexibility test, while sleep-related problems wereevaluated using the BEARS sleep screening tool (B = Bedtime problems, E = Excessive daytime sleepiness, A = Awakenings dur-ing the night, R = Regularity and duration of sleep, S = Snoring). Generalized linear models were used to examine the associationof overall physical fitness with the different components of sleep-related problems. The odds of experiencing sleep-related prob-lems decreased significantly with each kilogram increase in handgrip strength (odds ratio [OR] = 0.97, 95% confidence interval[CI] 0.94–0.99), and with each standard deviation increase in overall physical fitness (OR = 0.76, 95% CI 0.59–0.99). In contrast,despite not statistically significant, an increase in long jump appeared to reduce the sleep-related problems (OR = 0.91; 95% CI0.82–1.02), while a longer time in the 4×10-m shuttle run test might increase sleep problems (OR = 1.12; 95% CI 0.98–1.28). Inconclusion, greater levels of physical fitness, particularly muscular strength, may be key for reducing sleep-related problems,emphasizing the importance of personalized training programs.