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A new study suggests the effects of time zones can contribute to development of some cancers that are linked to change in biological clock.
Researchers examined data of 4 million adults from more than 600 countries who had been diagnosed with cancer between 2000 and 2012
They discovered that every 5 degree of longitude toward the west that a person lived from the eastern edge of their time zone increased risk of developing cancer.
Researchers said men who lived in the western-most region of a time zone had risk of developing prostate cancer, compared with men that lived in eastern-most regions of time zone.
They found that women living in the western-most region had risk of developing breast cancer compared to women living in eastern-most regions of time zone.
Normally, living things are supposed to be exposed to sun during the day and darkness at night but people stay indoor during the day and exposed to light at night, this can reduce melatonin at night, alter immune system and raise risk of developing cancer.