From CopperWikiblood pressure, digestive secretions and hormone production. The body clock, which is also found in other organisms, is mainly controlled by temperature and light. Bird migration is an example of how changes in temperature and length of day influence behavior.
 Why should I be aware of this?
- The cycle of sleep and being awake in humans is dependant on light and temperature. Any changes can affect the cycle and external factors such as alarms, changes in mealtimes, work or other demands can all take their toll
- Disruptions in Circadian Rhythm can cause jet lag, Delayed Sleep Phase Syndrome (DSPS), which creates a need to sleep longer and Advanced Sleep Phase Syndrome (ASPS), which causes early sleeping and waking.
- Though the most obvious function which our body clock controls is sleep, new research has discovered a whole host of functions controlled in this way, including control of the cycle of cell division, the starting point for cancer.
 Body clock and health
- The circadian clocks are the essential time-tracking systems in our bodies that anticipate environmental changes and adapt to the appropriate time of day. Once these rhythms are disrupted it can have profound influence human health and has been linked to obesity, diabetes, insomnia, depression, coronary heart diseases and cancer.
- More and more data are coming up ito show that a vulnerability or some sort of deregulation in the body clock is a primary cause for mood disorders.
 All about body clock
Controlling the daily rise and fall of sleep and wake hormones is the body’s master clock The body’s master clock – the suprachiasmatic nucleus – controls the daily rise and fall of sleep and wake hormones. Almost as small as a grain of rice, it sits in the brain, and ticks away a 24 hour day.
The hypothalamus in the brain controls the circadian rhythm. Light is so influential in sleep as the hypothalamus is near to the optic nerve. Sleep is controlled by neurotransmitters, which act on nerves in the brainstem and the spinal cord.
Researchers have identified the chemical switch that controls the genetic mechanism regulating people's internal body clocks. Although the process involves complex genes, the whole mechanism is controlled by a single amino acid - a building block of protein. 
It is hoped the discovery may lead to more effective drugs to treat sleep disorders and related ailments.
 New research findings
Now researchers at University of California, Irvine, have found that circadian rhythms regulate energy levels in cells, a fact which provides greater insights into the bond between the body's day-night patterns and metabolism. This discovery is believed will help create new ways to treat cancer, diabetes, obesity and a host of related diseases.
It has also been found that circadian rhythms and metabolism are closely inter-related. This ensures that cells function properly and remain healthy.
 90 degrees
Some studies have shown that night nurses with changing shifts are more likely to get breast cancer than those who work during the day, and shift work has also been linked to diabetes and obesity. 
- Body temperature is lowest before waking up in the morning, and highest in the late afternoon. A temperature of 99 degrees Fahrenheit might indicate fever at 7 a.m., but by 5 p.m. would be normal. 
- Heart attacks are twice as likely in the early morning as at other times. 
- Births peak in the morning and early afternoon. 
- So do suicides. 
- Body clocks are why doctors often prescribe taking medicines at certain times of day. For example, both aspirin and antihistamines work best taken in the morning. But some types of chemotherapy for cancer may be more effective and less toxic if administered at night. 
- People are much more likely to have sex at night just before they go to sleep than at any other time of the day. 
- If we were to live in total darkness, we would fall into a cycle of days that last up to 25 hours or longer. "Clock genes" control body temperature, the secretion of hormones and much activity at the cellular level—all of which are controlled by a master clock that runs on the longer cycle unless it is reset by the sun. 
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 Additional information
- The body’s daily clock
- Body Clock
- Body clock, metabolism link could lead to cancer treatment