Diurnal time course of sleepiness in Italian junior and high school students

Objectives: Despite the clinical and psychosocial importance of understanding the diurnal time course of sleepiness in children and adolescents, few ecological studies have investigated this issue. Following a previous research of ours on schooltime sleepiness and performance in primary school children, the aim of this study is to draw a similar profile in junior/high school students. Methods: A sample of 340 students from junior/high schools (age: 14.9 2.5) was recruited and sub-divided into two groups, according to age: Group 1 (10–13 years; N = 147) and Group 2 (14–19 years; N = 203). Sleepiness was measured through a five-points sleepiness scale, administered every hour from 8:30 am to 10:30 pm and before bedtime, one day a week for three weeks. Sleep quality was assessed through the Pittsburgh Sleep Quality Index (PSQI). Results: An overall significant increase of subjective sleepiness was found at the beginning of the schoolday and in the evening. Agerelated differences were found, in that global sleepiness was higher in Group 2. A significant “Age X Time of day” interaction was observed. No significant correlations were found between PSQI scores and “Age”. Conclusions: The presence of a vigilance trough in the early morning suggests to carefully consider the timing of school start. Adolescents feel less alert than children at several times of day, especially in the morning and in the early afternoon, but this result is not explained by reduced sleep quality. Further research should explore the psychophysiological mechanisms underlying subjective vigilance perception in teenagers