Clinical features of circadian rhythm sleep disorders in outpatients.

The clinical data of 86 cases of primary circadian rhythm sleep disorder (primary CRSD) were retrospectively examined and compared to 40 cases of secondary circadian rhythm sleep disorder (secondary CRSD), who had presented with some kind of psychiatric or medical disorder, and had exhibited sleep-wake rhythm disorders that were judged to be secondary CRSD based on sleep logs. The comparison of cases found that: (i) the mean age at first presentation to the clinic was significantly younger for primary CRSD compared to secondary CRSD; (ii) more secondary CRSD cases were unemployed than were Primary CRSD cases; (iii) more cases in the secondary CRSD group had a clear trigger for sleep-wake rhythm disorder onset than cases in the primary CRSD group; and (iv) the types of sleep-wake rhythm disorders in the primary CRSD group consisted of delayed sleep phase syndrome (DSPS), 72 (83.7%), non-24 pattern, 11 (12.8%), and irregular, 3 (3.5%). In the secondary CRSD group there were 25 (62.5%) cases of DSPS pattern, 1 (2.5%) of non-24 pattern and 14 (35.0%) with irregular pattern. The 56 (65.1%) cases with primary CRSD showed good response to vitamin B12 and bright light therapy; however, 28 (70.0%) cases with secondary CRSD did not respond to such therapies.