Correlation of hours of sleep with food consumption, physical condition and school performance: a preliminary analysis

Abstract

Introduction: Positive health promotion is a public health issue that must be considered through an early transdisciplinary approach. Integrated in a largest project about educational healthy lifestyles among school-aged children, this study aims to analyse the correlation of hours of sleep with food consumption, some physical condition parameters, such as body mass index (BMI), sedentary behaviour, and school performance. Materials and methods: Third and fourth grade students from several Portuguese primary schools were included. Data were collected during a class through a form focusing on socio-demographic and anthropometric variables, hours of sleep, sedentary behaviour (self-filled by the student); and school performance (assessed by the teacher). Child’s food consumption was registered through a one-day questionnaire and by the Mediterranean Diet Quality Index (KIDMED). The project was approved by an Ethics Committee. An informed consent was signed by the child’s legal representative. Data were analysed using the SPSS®-version 24.0. Results: Participants included 480 children (48.5% females and 51.5% males), with a mean age of 9.1 ± 0.37 years old. A preliminary analysis highlighted that hours of sleep (number of hours slept during the night prior to the assessment) appear not no correlate with the total score of KIDMED, as well as with the abdominal perimeter, percentage of fat mass, BMI, and Z-score (p > 0.05). Similarly, results showed no correlation between sleep and school performance. Interestingly, there was a statistically significant (p < 0.01) but low anti-correlation (R=−0.17) between hours of sleep and the sedentary behaviour (number of hours sitting during hobbies, per day). Discussion and conclusions: The hours of sleep may be affected by daily sedentary time and sedentary behaviours, a finding that deserves further analysis. Conversely to what expected, it seems there is not a statistical correlation between hours of sleep and food consumption, as well as with physical condition parameters and school performance. However, more than the number of hours slept, further studies should focus on the quality of those hours, since sleep quality as well sleep disturbances can increase the levels of tiredness and, consequently, can lead to more sedentary lifestyles.