FDA clears first drug for blindness sleep disorder

U.S. health regulators have approved a first-of-a-kind drug to treat a sleep disorder that mainly afflicts the blind.

The Food and Drug Administration approved Hetlioz capsules for patients who have problems sleeping because they can't detect light. The condition, called non-24-hour disorder, is estimated to affect up to 100,000 Americans, most of whom are totally blind. Hetlioz is the first FDA-approved treatment for the condition.

The most common side effects of the drug include headache, nightmares and respiratory and urinary tract infections. The drug labeling warns that Hetlioz causes drowsiness and can interfere with performing basic tasks and mental alertness.

Analysts estimate the drug's annual sales could exceed $350 million.

Washington DC-based Vanda Pharmaceuticals markets one other drug for schizophrenia.

Company shares rose nearly 5 percent in afternoon trading.