Team finds clue to helping insomniacs get better sleep

The number of insomniacs in Korea is growing amid mounting social stress, with up to one-fifth of Koreans suffering from the illness.

If the sleeping disorder continues, it can cause problems not only in the immune system but also in the autonomic nervous system, which could progress to a mental disease such as depression and excessive anxiety.

A team of Korean researchers has discovered a clue that could lead to better treatment of insomnia. Led by Dr. Shin Hee-seop, head of the Center for Recognition and Sociability at the Institute for Basic Science, the team said Tuesday that they succeeded in artificially regulating in animal brains a sleep spindle, a brainwave that enables people to have tight sleep. Sleep spindles are known to appear less in insomniacs, and this was the first time that the effect of sleep spindles was confirmed.

The researchers transplanted optic fiber onto the brain of lab mice that were manipulated to respond more sensitively to light, so that light can be directly beamed onto the brain of the mice. Then they exposed light of 3 hertz, or the same frequency as sleep spindles, onto the nerve cells called nucleus reticularis thalami in the brain.

As a result, they confirmed that the mice’s brainwaves stabilized and their sleep spindles and sleep hours increased simultaneously. The mice that were manipulated to have increased sleep spindles get tighter sleep even when sleeping the same hours than ordinary mice, meaning that even without the use of anesthetic agents such as Propofol, the regulation of brainwaves alone could allow people to have tight sleep.

The findings are expected to provide an important clue to the development of therapy to treat sleep disorders among humans. Team leader Shin said, “The study was the first to suggest that a reduction of sleep spindles is a major cause of sleep disorder,” adding, “It will serve as a catalyst for discovering the relationship between the brain and sleep electroencephalography.”

The study was first published online Monday in the Proceedings of the National Academy of Sciences.

enhanced@donga.com