The purpose of this study was to determine conditions of dining behaviors, sleep patterns, rates of obesity and intake of snacks and self-purchased snacks deriving from the lack of sleep in academic high school students. The anthropometric characteristics, height and weight (p<0.05), and the distribution of obesity index (p<0.001) showed significant differences between males and females. Dining scores for both male and female students decreased as the frequency of day time napping increased. Although, there was no significant difference in obesity-related "lack of sleep" between males and females, the rate of "being overweight" was slightly higher in female students who indicated that they experienced a "lack of sleep" than female students that indicated "no lack of sleep". While, whether intake of snacks and self-purchased snacks or not, day time napping frequency affected not to male students. However, the frequency of day time napping among females who ate snacks one or more times a day was higher (p<0.05), and a greater frequency of eating self-purchased snacks correlated with a greater frequency of day napping (p<0.01). Consequently, lack of sleep was identified as one of the factors increasing the frequency of intake of snacks and self-purchased snacks in females. Thus, this study suggests that dining behavior guidance should be given along with systematic and continual nutrition education so that the intake of snacks and self-purchased snacks can be moderated to optimize the physical and mental growth and development of adolescents.