Preschoolers who are exposed to bright lights before going to bed might have problems falling asleep, a new study found. According to the research paper, published in the journal, Physiological Reports, one hour of exposure to bright light before bedtime can almost completely halt the production of melatonin, the hormone responsible for sleep.
“Although the effects of light are well studied in adults, virtually nothing is known about how evening light exposure affects… preschool-aged children,” said lead author of the study, Dr. Lameese Akacem, a CU Boulder instructor and researcher in the Sleep and Development Lab.
Dr. Akacem and his colleagues studied the hormonal changes in preschool children once they were exposed to bright lights. The main focus of the study was on the hormone responsible for inducing sleep and controlling the sleep and wake cycle, called melatonin. The hormone is also essential in regulating temperature, blood pressure, and glucose metabolism.
For the study, researchers recruited a group of ten healthy children aged 3 to 5 who were given a regular sleep schedule which they had to follow for five days. Five days were enough for the children’s metabolism to establish a pattern for their body clocks to follow.
Researchers also analyzed the children’s saliva several time throughout the day to measure the baseline levels of melatonin. On the sixth day, the children’s homes were converted into low-light “caves” with windows covered with black plastic. In addition, the regular lighting was swapped for low-wattage light bulbs.
During the following evening, the participants played with magnetic tiles on top of a light table emitting 1 thousand lux of light for nearly one hour. After the experiment, researchers collected samples once again.
When comparing the two nights, researchers found that melatonin levels were nearly 88 percent lower after bright light exposure. These levels remained low almost an hour after the lights were turned off.
The researchers, however, acknowledged that the study had some limitations including the small sample size of participants and the brighter lights, which is not generally emitted from electronics.
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