Triazolam causes a phase-shift of the circadian rhythm of locomotor activity in golden hamsters. We attempted to treat two patients with delayed sleep phase syndrome (DSPS) with triazolam. In one male patient we administered triazolam when the sleep phase began to delay after chronotherapy. Triazolam combined with chronotherapy enabled him to normalize and stabilize his sleep-wake cycle. But in the other female patient despite normalization of her sleep-wake cycle, she became depressive and did not continue taking the drug. In some cases triazolam is useful for the treatment of DSPS, but in others, triazolam induces a depressive state.