Delayed sleep phase disorder (DSPD) is a circadian rhythm sleep disorder characterized by a substantial delay in the major sleep period, resulting in difficulties falling asleep and awakening at a socially desirable time in the morning. This study is the first to investigate the NEO-Personality Inventory-Revised profile of young adults with DSPD. The study includes 40 patients diagnosed with DSPD (mean age = 20.7) and 21 healthy controls (mean age = 21.1). Results showed that young adults with DSPD scored higher on Neuroticism, lower on Extroversion, and much lower on Conscientiousness than the control group. Assessing the personality profile of young adults with DSPD before initiating treatment might provide useful clinical guidance regarding the individual needs for follow up during treatment.