The study investigated the efficacy of the treatment of patients with delayed sleep phase syndrome (DSPS) through hospitalization, given social cues and their psychological characteristics, using a picture-frustration study. The participants were 22 DSPS patients with school refusal during adolescence, consisting of 13 boys and 9 girls (mean age ± SD = 16.0 ± 1.4, range = 13–18). Over 90% of the DSPS patients with school refusal showed improvements in their sleep-wake rhythm (S-W) just after hospitalization. Over 50% of them maintained their improved S-W after discharge and attended school. The picture-frustration study for DSPS patients with school refusal, especially in patients who showed no improvement in their S-W and school refusal after discharge, showed low aggression, low expression of their dissatisfaction, high suppression of their emotion, low social interest and high self-criticism. Patients who did not show improvement in their S-W through hospitalization have psychological problems such as those mentioned above. They may therefore need to take psychological intervention such as self-assertion training.