Tips for sleeping well

One of the keys to getting a good night's sleep is to get into a regular routine, such as sleeping and waking at the same time every day, said Han Jin-kyu at the Seoul Sleep Center.

"Exposing yourself to sunlight in the morning helps you to wake up," said Han. "But many people get up before the sun rises and drive to work or hop on the subway, thus lowering their exposure to sunlight.

Staying up late also destroys the body's natural biological rhythm."

"When you sleep, your organs also rest and secrete much-needed hormones that boost the immune system, suppress excessive drives to eat, and control the emotions," he added,

A lack of sleep weakens the immune system, impairs memory, dries the skin, shortens tempers, often leading to depression if it becomes a regular pattern, he added. Sleep-deprived people also secrete more cortisol, the so-called stress hormone, which drives them to seek food and can lead to obesity.