The influence of the time of the day is important for many vital functions, but also obviously to regularize lifestyles, and improve performances in every working environment, but also to improve sports performances, even for adolescents.
The influence of time of day on the performance of adolescent swimmers, study published on the Chronobiology international, analyzes: "The study aimed to investigate the eﬀects of time-of-day, chronotype, and gender differences on the relationships between anxiety, depression, sleep quality, and swimming performance of normally diurnally active adolescent athletes.
They performed 50 m and 400 m front crawl trials twice, at 08:00 h and 18:00 h, with an interval of 48 h in a 50 m swimming pool. Chronotype, depression, anxiety levels, and sleep quality were accessed by questionnaires. No effect of time-of-day was observed in girls for the 50 and 400 m trials.
The swimming performance of boys was similar in the 50 m trials independent of time- of-day, but in the 400 m trial the performance time was better in the evening compared to morning. The best evening performance was observed among N-types.
Linear regression analysis of the data of all participants revealed a positive correlation be tween sleep quality and anxiety level and sleep quality and depression level." The study also explained: "We conclude that time-of-day can influence the performance of adolescent swimmers that differs with the distance of the trial and by gender.
We also demonstrated the importance of sleep quality among adolescents swimmers as a factor that can influence anxiety and depression and thus consequently affect their performance."
History of the time of the day
Ever since man began to use the sundial, the length of the day was divided into what we now call hours.
Babylonians and Egyptians used this system, but it was not the same as the one we know today. The division of the day into 24 hours dates back to ancient Egypt (1800-1500 BC); the hours of the day were 10, marked by the shadow of the sundial gnomon from sunrise to sunset.
To these were added another two hours respectively for dawn and dusk, parts of the day in which the sundial gave no indications. The night hours are marked by the passage of the Decans in the night sky. Summer nights in Egypt last eight hours, during which 12 Decans follow each other, marking 12 hours.
In the winter nights a greater number are observed, but only the first 12 were counted. This complex mechanism led to the division of the day into 24 hours. Greeks and Romans used temporal hours: day and night were both divided into twelve parts, starting respectively from sunrise and sunset.
Thus the first hour of the day corresponded to dawn, the sixth hour more or less at noon, the twelfth at sunset and the same, but starting from sunset, it happened for the night. This subdivision based on the hours of light and those of dark meant that the duration of the summer hours was not the same as the winter hours and that of the hours of light was different from the hours of darkness. Just to give an example, in summer an hour of light could last 80 minutes and 40 minutes instead of darkness.