Do You Know Nutrition: Food, sleep affects circadian clock

By Phylis Canion
July 22, 2014 at 2:22 a.m.

Can food affect our internal body clock, and can it have anything to do with diabetes and weight gain?

All animals and plants have a built-in circadian rhythm - our internal body clock that is also known as our circadian clock. The word circadian comes from the Latin word meaning "about a day" and involves two critical pathways. The first pathway, and the most important, responds to light and has been well-characterized.

The brain's internal circadian clock is centered in the hypothalamus region of the forebrain and uses zeitgebers - time-givers - to naturally synchronize itself to within just a few minutes of the Earth's 24-hour rotation cycle.

Humans are diurnal animals and are naturally active during daylight. The second pathway, which is less understood, is how the body responds to food. Although the research data seems to be poorly compiled, there are body functions that have been linked to the circadian rhythm.

Dietary manipulation may play a valuable role in adjusting the circadian clock, according to Dr. Makoto Akashi of the Yamaguchi University in Japan.

Researchers found insulin, a pancreatic hormone, is secreted in response to feeding and may be involved in resetting the circadian clock. Researchers at the Brigham and Women's University Medical Center in Boston concluded that periods of irregular sleep resulted in a rise in blood glucose and a drop in metabolic rate. While the brain was originally thought to be the main controller of our circadian clock, the liver and the intestines have their own circadian rhythm, like the pancreas.

As an example, peak energy level for the stomach occurs between 7 and 9 a.m.; hence the reason breakfast is the most important meal of the day. While it is common knowledge that the stomach secretes digestive acid with each meal, it is still somewhat a mystery as to why the stomach secretes two to three times more acid from 10 p.m. to 2 a.m.

Perhaps the brain is the conductor of the symphony and coordinates the action of the stomach and other organs. Our circadian rhythms can be disrupted by jet lag, lack of sleep, shift work, some medications and eating at unusual times. Abnormal circadian rhythms are linked with problems like insomnia, fatigue, depression and Type 2 diabetes. Now, more studies are linking a disruption in circadian rhythms to weight gain. The secret: Get enough sleep.

Thought for the week: "One's mind, once stretched by a new idea, never regains its original dimension." - Oliver Wendell Holmes

Phylis B. Canion is a doctor of naturopathic medicine and is a certified nutritional consultant; email her at This column is for nutritional information only and is not intended to treat, diagnose or cure.



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