Sound Sleep and Secret of Growth Hormone

˝You should go to bed.˝ ˝No, I want to watch TV more.˝ Lee, a young mother living in Yeongdeung-po, Seoul, has haggling with her 6-year-old son every night.

Lee has heard that the habit of going to bed early promotes generation of human growth hormone, or HGH. But her son is not cooperative at all, sitting before the TV set showing dynamic images. He goes to bed only after 11:30 p.m. and she is worried if he cannot grow strong enough.

But the idea that HGH secrets between 10:00 p.m. and 2:00 a.m. following day is not true. Human body generates HGH whenever young children are deep in sleep. The hormone in fact is generated even when they are awake.

Then why parents try to send children to bed early against the little ones` will? According to the scientific fact, when they go to bed must be irrelevant as long as they sleep well. Here, researchers explain why children must go to bed early.

▽Harmful Environment and Growth = TV dramas aired late at night lure many small children to the TV set. Some are addicted to the Internet or video games, and some others wait for their working parents to come home. These are all so-called `harmful sleeping environments.` The harmful environments lead to lack of sleep, which could further result in a serious disorder when children grow up.

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˝Children who do not sleep long enough tend to have a problem with concentration and control of emotion, getting angry or disappointed easily,˝ said Karl Hunt, Director at the Sleep Disorder Research Center under the U.S. National Institute of Health. He citied extracurricular activities, assignment, TV, the Internet, mobile phones and e-mail as the reason for lack of sleep.

Dr. Claude Lanfan, Director at National Heart, Lung and Blood Research Center under NIH, also warned that the bad sleep habit could lead to heart, pulmonary diseases and obesity when they grow up.

A research team at Harvard University recently released in NIH publication and the Neuron results of their study, which found that lack of sleep is related to degrading abilities in memory, instrument playing, exercising and skill learning.

Children often look just okay even when they did not sleep well last night. It is because their brain and muscles have not grown fully enough to feel fatigue. That is why little elementary school students hardly doze in class. Sleep disorder develops gradually. When their children have a problem with concentration, therefore, parents must suspect if they have sleep disorder.

▽Going to bed early is good for health = Though doctors acknowledge that there are some individual differences, they say that according to biorhythm cycles, newborn babies should sleep for 15 –20 hours a day on average, while two- or three-year olds are supposed to sleep for 11-12 hours. As children grow up, their sleeping time decreases. And twelve- to fourteen-year old children have a sleep for eight hours, similar to that of adults.

If the bedtime is deferred, however, biorhythm can be broken. If you go to bed around midnight and wake up at 8:00 in the morning, the quality of sleep is not good and real sleeping time is only five to six hours, though you slumber for eight hours. It is because sunlight interrupts deep sleep. In addition, if you continue to delay your bedtime and fall asleep at dawn, you can suffer from Delayed Sleep Phase Syndrome (DSPS). In this case, your Human Growth Hormone (HGH) level drops considerably.

Unlike adults whose sleep cycle is concentrated during the night, five to ten year old children’s biological clock is set for them to feel sleepy around nine to ten in the afternoon. So they should go to bed before ten o’clock at least and have a heavy sleep.

▽Having regular bedtime = Before ten o’clock, parents should send children into their bed room and have them make the bed. It reminds them that it’s time to go to bed.

Even if children insist on watching TV, parents should reject it flatly. Entertainment devices including PCs had better be moved out of children’s rooms.

Lighting during sleep disturbs deep sleep, so you should avoid it.

However, if children are scared of the dark, dim light such as a flashlight (15 lux) could work. Leaving children in the dark, though they are scared, could result in emotional disorder.

In order to minimize the disturbance of sleep by the light, it should be installed on or under a table, the height of which is lower than the height of children’s eyes. If children are not afraid of the dark when they wake up, the light had better be turn off right after they fall asleep.

If parents come home late, they should call children and persuade them to go to bed. This is to prevent children from being obsessed by a sense of fear that the parents could not come home. By hearing their parents’ voice, children have emotional security.

In addition, there are some other ways to help children have a deep sleep. You can use curtains that well block sunlight or soundproof windows. The humidity should be maintained at 60% and the temperature at 22 degrees Celsius in bedrooms.

(Information from Prof. Hong Seung-bong at sleep disorder clinic of Samsung Medical Center, Prof. Sin Chul of Korea University Medical Center in Ansan, and doctor Kim Seok-ju of Seoul Metropolitan EunPyeong Hospital.)

corekim@donga.com