Influence of different light intensities during the day on the motor activity in adolescents

This study investigates the impact of varying light intensities throughout the day on motor activity levels in adolescent girls aged between 14-16, who are students at a boarding school. The study lasted for three weeks, with each week consisting of four days. During this period, participants experienced three different lighting conditions from 07:00 to 18:00. These conditions included: standard light intensity in real-life settings, wearing blue-blocking glasses, and spending at least 1.5 hours outdoors daily for natural light exposure. The aim was to understand how modern lighting sources can replace natural lighting and to assess the influence of the lighting spectrum on the daily rhythms of motor activity. Restriction of blue light led to an increase in the average daily level (MESOR) of the intensity of movements denoted by HPIM (High Proportional Integrative Measures), as well as a decrease in the amplitude of the circadian rhythm ZCM (Zero Crossing Mode). This confirms the important role of blue light during the daytime as a Zeitgeber of the circadian rhythm. When adolescents spent at least 1.5 hours outside, mostly in the afternoon, the acrophases of ZCM’s 24-hour rhythm shifted half an hour later.