Telephone interviews have been used extensively as a tool to explore and assess sleep disorders and psychopathological conditions. The aim of this study was to set up and validate a telephone interview aimed at assessing the correlation between mood and sleep variables in adolescents. The study included 16–18 years subjects. A total of approximately 4,000 calls were made; 529 adolescents were finally enrolled. The questionnaire was divided into two parts: the first one focused on affective variables, the second one explored sleep variables. A factorial analysis was carried out to explore the structure of the questionnaire according to two factors: the first, which we labeled ‘‘affective factor’’, and the second, ‘‘quality of sleep’’. A positive correlation was found regarding the feeling of wellbeing on awakening. A negative correlation was found between feeling of wellbeing on awakening and daytime drowsiness. In adolescence, increased daytime sleepiness seemed to correlate with worsening mood.