Mice displayed an earlier onset of breast cancer and weight gain when there was a disruption of natural light-dark cycles of day and night. Shift work is necessary in many professions and provides them with some conveniences but straying from the natural cycle of sleeping at night and waking during the day has serious health consequences. Mice subjected the same schedule as shift workers experience 20 percent more weight gain and developed breast cancer earlier in life. Circadian rhythms are the 24-hour biological cycles that go on within the bodies of man and mice. Mirroring the circadian disruptions that humans experience can be studied in mice to identify the factors that are similar and translate to the human situation.
http://youtu.be/TW3_si6IvDA
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