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Our bodies have a built-in 24-hour cycle, which doctors call the circadian rhythm. Researchers have started to realise that these natural rhythms also apply to medical conditions and have implications for treatment. In the 1980s it was discovered that some cancer patients had significantly reduced side effects if chemotherapy was given at the right time of day. Asthma is at its worst at 4am, when cortisol levels in the body are at their lowest, but trials suggest drugs taken at 3pm ensures they’re at optimum level during this crucial period of the night. Heart attacks often happen shortly after waking up because blood pressure surges at that time; two drugs have been developed that can be taken last thing at night, but whose action is delayed several hours until they are most needed. The medical profession is starting to use the term chronotherapy for such treatments that work in harmony with the body’s natural time rhythms. The study of the process is chronotherapeutics.

As with so much in the infant field of chronotherapy, theory lags practice.

Economist, Dec. 1999

Last year a trial using chronotherapy to treat cancer patients in France, Italy, Belgium and Canada found that patients given drugs at the optimum time in their day cycle of cell growth had far fewer side effects.

Independent on Sunday, Feb. 2000

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Page created 26 Feb 2000