This study used a cross-sectional study to collect data from university students using a selfadministered questionnaire. The data were collected in September-December 2013. A purposive sampling method was used to select participants from the first year in University of Phayao. Participants were eligible for inclusion if they were (a) self-reported between 18 - 21 years (b) selfreported single marital status, and (c) undergraduates students in School of Medicine.