After breaching the 300,000-mark, the number of people with sleeping problems has spiked more than 40 percent over the past five years, with the annual increase rate averaging 8.7 percent.

The number of sleep disorder patients is widely estimated to far exceed the official tally as a considerable number of people opt not to see the doctor.

Buoyed by the spike in the number of sleep disorder patients, the local market for insomnia treatments, especially non-psychotropic drugs, has been rising sharply, according to industry watchers.

That's because a growing number of people with sleep problems are turning to non-psychotropic medications, which lead to fewer side effects and are less addictive, they said. Existing treatments are mostly psychotropic, which affects the mind, emotions, and behavior of patients.

To meet the growing demand, two local pharmaceutical companies -- Kuhnil Pharmaceutical and CJ HeathCare -- have put non-psychotropic sleeping pills on the market with their sales rising sharply.

Sales of Kuhnil Pharmaceutical's Circadin more than doubled in the one-year period after it hit local drugstores in July 2014, with shipments reaching 3 billion won ($2.62 million) in 2015.

A CJ HealthCare official expected the market for non-psychotropic sleeping pills to grow significantly as patients are concerned over side effects of psychotropic mediations and their addictiveness.

Kwang Dong Pharmaceutical, a major drug company here, has also started selling an over-the-counter sleep aid targeting mainly women. Female sleep disorder patients account for 58 percent of the total in Korea. (Yonhap)