Circadian rhythm is affected by numerous things, one of which is shift work. I know this first hand because I have a close friend who works very odd hours. For example, he works twelve hour shifts. He will work two days on the day shift and then have two days off. Then he will work two night shifts and have two days off and so forth. His sleeping schedule is constantly changing. In an instance like this it can be incredibly difficult for the body to develop a sleeping pattern because of the upset in the natural circadian rhythm.
Upsets in the circadian rhythm can lead to health problems such as sleep disorders.
Study of the circandian rhythm shows that if someone is left in a continuously dark room for days on end, they will still display a circadian rhythm. This shows that light is not the only factor in the sleep wake cycle. An area in the brain called the suprachiasmatic nucleus, or SCN contains what is called the "master clock".
"The SCN contains about 20,000 nerve cells and is located in the hypothalamus, an area of the brain just above where the optic nerves from the eyes cross."
The master clock is what controls our bodies circadian rhythm. It tells our body when to increase the excretion of melatonin and when to stop.
A diet, high in fats, may lead not only to the gain of weight, due to the excessive intake of calories, but it can affect circadian rhythms, or biological clock of each people.
People, who are suffering from circadian rhythm disorder, are unable to sleep or to wake up at normal hours and to go to work or to school.
Researchers have shown, with the help of lab-rats, that there is a cause-effect relationship between nutrition and the imbalance of the biological clock.
It was tested whether the biological clock affects the way of adiponectin (a protein hormone that regulates several metabolic processes) to the liver.
It was found that the lab-rats fed with low-fat diet, the circadian clock has not been affected, while in lab-rats fed with a high fat content diet, it was a slowing down of the biological clock.
Researchers claim that obesity is established not only because of high fat content, but also because of metabolic disorders.