ABSTRACT
Although it is well known that sleep disturbances can be developed in complete blindness, normally entrained circadian rhythm was observed in the majority of patients with partial blindness. Here, we describe a case with circadian rhythm sleep-wake disorder in partial loss of light perception. A 58-year-old man presented with difficulty in sleep initiation and excessive daytime sleepiness after retinal surgery. The electroretinography revealed partial impairment of light perception in the right side and preserved light perception in the left side. He was diagnosed as circadian rhythm sleep-wake disorder due to impaired light perception. While taking 2 mg of melatonin regularly at 9 every night, his sleep cycle and difficulty in sleep initiation were gradually improved and became fully normalized after 2 weeks. Circadian rhythm sleep-wake disorder could be developed even in partial blindness. Melatonin supplements could effectively improve the circadian rhythm sleep-wake disorder in partial blindness, like as in complete blindness.