There has been little epidemiological evidence that has comprehensively clarified whether alterations in lifestyle, such as sleep quality and dietary intake, explain changes in the skin condition of healthy young adults. Therefore, the aim of our study was to elucidate the association between skin condition and lifestyle behaviors such as diet and sleep, after statistically controlling confounding factors. The subjects were 54 participants who were aged 20-32 y, and who attended college in the Kanto region (in Japan). Transepidermal water loss (TEWL) was obtained by putting a probe on the skin surface based on the European Society of Contact Dermatitis guidelines for TEWL measurements. Self-administered questionnaires on demographic characteristics, dietary habits, and health status, such as sleep condition, depression, and fatigue, were handed to participants on the day of measurement. We found that lower sleep efficiency was significantly associated with higher TEWL (p=0.023), while other demographic factors, dietary intakes, and eating behaviors were not (p>0.05). This significant association remained unchanged after controlling for confounding variables, such as sex, BMI, and dietary intake. Our findings may have important implications in the development of valuable health strategies that may suggest behavior modifications for young to middle-aged men and women.