9. Working the night shift
Nearly 15 percent of Americans work the night shift, and according to a number of large studies, this late-night work may increase cancer risk in some people. In a study of mice, MIT researchers found that two genes tasked with controlling cells’ circadian rhythm — the 24-hour cycle that regulates when we go to sleep and when we wake up — also function as tumor suppressors.
Given that the body’s central circadian rhythm (also known as the body’s “master clock”) works primarily in response to light and darkness in the environment, night shifts interfere with the body’s natural circadian rhythm. In the study, researchers divided mice into two groups; one group of mice went through a normal light schedule (12 hours of light and 12 hours of darkness). Researchers exposed the other group to an extra 8 hours of light every 2 to 3 days. Compared with the control group, the mice exposed to abnormal lighting experienced faster and more aggressive tumor growth.