Experts are evaluating the possible link between childhood leukemia and too much light at night.

More and more children are diagnosed with leukemia, following a noticeable spike happening in those younger than 5 years old. For them, the risk of developing this cancer increased by more than 50 percent during 1950-2000.

Why leukemia strikes children is not known. However, experts think environmental factors may be the source of the 20th century rise. If they are right, then it may be possible to identify causes -- like light at night -- and prevent the disease. Researchers point to light as one of these factors because modern people are exposed to more light than in the past. Light at night disrupts the natural hours of darkness our bodies need to produce proper levels of melatonin.

Sleep -- also known as natural circadian rhythm -- is an important part of overall health because of this hormone, which protects DNA from damage. Experts say low melatonin has been known to instigate and promote cancer growth.

Several studies have concluded that people who work at night are more likely to develop breast cancer. Also, experts note that blind people, who are not vulnerable to light at night, have a lower incidence of cancer.

Researchers plan to look at the association between biological clocks and light receptors in the human eye, and how sleep patterns, alertness, mood, physical strength and blood pressure are affected. They also will examine another possible cause of childhood leukemia -- magnetic fields, which also may decrease melatonin levels.

EurekAlert September 8, 2004

Dr. Mercola's Comments:

This link between light and leukemia isn't surprising to me because light exposure at night can reduce melatonin levels, which increases your risk of cancer. Young children are exposed to several forms of light at night -- including night-lights and television. Children, teens and adults should not watch TV before bed. Better yet, get the TV out of the bedroom or even out of the house, completely. It is too stimulating to the brain and it will take longer to fall asleep. When light hits the eyes, it disrupts the circadian rhythm of the pineal gland and production of melatonin and seratonin. There also should be as little light as possible in the bedroom and, if you get up in the middle of the night, in the bathroom. If you are lacking melatonin, I do not recommend supplements. It is best to increase levels naturally with exposure to bright sunlight in the daytime (along with full spectrum fluorescent bulbs in the winter) and absolute complete darkness at night. One of the other important things you can do to maximize the production of melatonin and decrease your risk of cancer is to make sure that you have exposure to bright sunlight during the daytime. Indoor lighting just won’t cut it. At night it is important to sleep in pitch dark. You should not be able to see your hand in front of your face ten minutes after you turn out the light. Most people will require black out shades and/or drapes to achieve the level of darkness. Maintaining your internal clock is important to health. Simply, a full night's sleep is key to your health. Related Articles: Sleep In TOTAL Darkness to Decrease Cancer Risk If Your Body Clock is Disrupted it Can Speed Cancer Growth Want to Prevent Cancer? Make Sure You Sleep Well Good Night's Sleep Essential for Immune System Get Enough Sleep to Avoid Diabetes