This study investigated the effects of melatonin administration on circadia
n rhythm sleep disorders, and aimed to clarify clinical characteristics of
melatonin responders. The subjects were 46 patients with circadian rhythm s
leep disorders: 30 Delayed Sleep Phase Syndrome (DSPS) and 16 non-24 h slee
p-wake syndrome (non-24). Patients took 0.3-1.0 mg of melatonin 5, 3 and Ih
before habitual bedtime. Seventeen patients responded to melatonin (12 DSP
S, five non-24). Comparison of clinical background between responders and n
on-responders revealed that the responders were characterized by short tota
l sleep time and later onset age of clinical symptoms.