Psychosomatic disorder may be related to circadian rhythms in physically healthy students

Students suffering from subjective psychosomatic disorder often have basic lifestyle problems. We examined 30 healthy students aged 21-22years old. Salivary samples were collected from the subjects at home five times per day (20:00, 24:00, 04:00, 08:00 and 12:00h). We assessed melatonin secretion patterns by fluorescence enzyme immunoassay and cortisol secretion by ELISA. We assigned the subjects to regular, semi-regular and irregular circadian rhythm groups based on whether melatonin secretion was high until midnight. A self-assessment questionnaire addressing psychosomatic disorder was completed by the same students. The subjects rated their psychosomatic symptoms twice per day (08:00 and 20:00h). The irregular group showed lower cortisol awakening response, but high cortisol concentrations at 12:00h; this group also reported more subjective health complaints related to psychosomatic stress compared with the regular group. Our findings suggest that psychosomatic disorder is associated with circadian rhythms in Japanese students.