"Even after work, it is hard to find time to catch up on sleep. My baby daughter crawls up to me even when piles of household chores await me with my wife, a pharmacist, away," said Kang, an English teacher at Sangil High School in Bucheon, just west of Seoul.

When his baby falls asleep, then it is time for him to start preparing for both regular and supplementary classes.

"But she usually wakes up and cries in the middle of the night."

Kang is among many South Koreans suffering from sleep disorders, including insomnia and sleep deprivation, and their health effects in an highly competitive society.

According to the latest data compiled by the Organization for Economic Cooperation and Development, the average South Korean sleeps seven hours and 41 minutes a day -- 41 minutes less than the OECD average and the lowest figure among the 26 countries surveyed.

Notorious for long working hours and heavy workloads, South Korea has also seen a steep rise in the number of citizens with sleep disturbance.

The data from the National Health Insurance Service show that the number of South Koreans with sleep disorders was tallied at 721,000 in 2015, a sharp increase from 325,000 recorded in 2011.

The amount of their related medical expenses reached 50.2 billion won ($43.6 million) in 2015, up 57 percent from 2011.

Choi Ji-ae, a psychiatrist, said sleep disorders can be caused by various factors, including work-related stress, over-intake of caffeine and the constant use of smart gadgets such as tablet PCs and smartphones even during bedtime.

"People get stressed out during work or within their family boundaries, or they may have concerns about their future or current financial status, all of which would keep them from getting good, restful sleep," she told Yonhap News Agency.

"Some chat over the phone or watch TV into the wee hours of the morning, or play with social media or surf the net -- all these activities stimulate brain activity and impede sleep."

Choi, in particular, stressed that it is important to designate your bed as a space dedicated solely to sleeping -- not for other activities that would leave your brain cells continuously running.

"Our bodies are designed to spend about a third of our lifetime sleeping. If we do not sleep, it is like having a machine run without a pause," she said.

"If we fail to allow our bodies and brains, which worked actively during the day, to rest, this will have side effects."

With the steady rise in the number of South Koreans lacking sleep, the sleep industry has been growing over the recent years, with the market currently estimated at 2 trillion won ($1.74 billion), according to the Korea Sleep Industry Association.

Such businesses sell various sleep care products and services to people in pursuit of a deep, sound sleep.

The industry has been gaining much attention to the extent that there is a newly coined word -- sleeponomics, a compound word of sleep and economics, an official told Yonhap News, requesting anonymity.

"The industry has been expanded to include those producing various products ranging from bed sheets to illuminations ... We anticipate that through the convergence of technologies, the industry will continue to boom."

Tapping into the sprawling industry is First Class Co., a "healing" cafe franchise that has run less than 10 shops mostly in the Seoul metropolitan area.

The unique cafe features partitioned premium massage chairs that look like the first-class seats on a plane. Friends and couples ensconced in the chairs were seen drinking tea or coffee, getting a massage or taking a nap.

The rates for the "first-class" service, including beverages, are 9,900 won ($8.66) for 30 minutes and 13,000 won for 50 minutes.

"I enjoy coming to this cafe as I am always lacking in sleep due to a heavy workload, frequent night shifts and long commuting hours," said Bae Seok-wan, a 29-year-old office worker in Seoul. "I think I will frequent this serene place as I can take a break and get a massage."

Club Comics is another healing cafe in the bustling university neighborhood of Hongdae in central Seoul where people can relax or snooze on a relatively spacious floor partitioned off for each customer. At this second-floor shop, clients can also enjoy a wide assortment of comic books.

On weekdays, it costs 2,400 won to stay in the cafe for one hour.

"There has been a gradual increase in the number of office workers coming here for a break," said Park Jung-eun, a 42-year-old manager of the cafe. "To make sure that this place is comfortable for all of our customers, we always try to make it neat and tidy, ensure the optimal lighting and keep bringing in new comic books." (Yonhap)