Demographic and sleep characteristics, self-ratings (mean, standard deviation (SD)) of early (EC), intermediate (IC) and late chronotypes (LC).

Abbreviations:PSQI, Pittsburgh Sleep Quality InventoryESS, Epworth Sleepiness ScaleKSS, Karolinska Sleepiness ScaleBDI, Beck Depression Inventory.*P ** P a expressed in number of school and study years.b expressed in typical number of cigarettes per day.c expressed in typical number of standard alcoholic drinks per week.d sleep/wake cycle two days before the measurement day.e sleep/wake cycle one day before the measurement day.Demographic and sleep characteristics, self-ratings (mean, standard deviation (SD)) of early (EC), intermediate (IC) and late chronotypes (LC).