The circadian rhythm is the body's internal biological processes that keep it synchronized with the day and night cycles. It responds to the presence of light to tell a person that it's time to wake up, and it makes him feel sleepy when it gets dark. It regulates not only sleep but also hunger, hormone production, and body temperature. Messing with this internal process leads to a ton of complications, such as depression, obesity, and seasonal affective disorder. (Related: Nature shows us how important circadian rhythm is to our overall well-being.)
Circadian disruption causes a domino effect leading to cancer
When you force yourself to stay up or sleep in longer, it disrupts the circadian rhythm. This means that your internal biological processes are more likely to go haywire, even if you don't immediately notice it.
The research, conducted by a team from Pennsylvania, found that people whose circadian rhythms were regularly thrown off were more likely to get cancer because chronic circadian disruption had an effect on tumor growth.
To test this hypothesis, the researchers exposed cells to a hormone called dexamethasone, which is able to disrupt the circadian rhythm. Upon exposure, they found that the cells skipped a phase in their life cycle and go straight to the creation of more DNA in preparation for cell division. This uncontrolled cell division is what causes tumor growth.
This means that circadian rhythm disruption leads to the acceleration of cell division, making the body more susceptible to cancer-bearing tumors.
The disruption also weakens the fight against cancer
On top of this, the production of melatonin, a sleep hormone with cancer-fighting properties, increases when the sun goes down to tell people that they need to sleep. Staying up, either due to a shifting work schedule, jet lag, or even a sleep disorder, suppresses melatonin, making the body more vulnerable to cancer.
To further test their hypothesis, the researchers disrupted the circadian rhythms of mice and rats. They found that it was detrimental to their health and caused an array of behavioral and hormonal problems such as weight gain, cognitive problems, and tumor development.
Based on their findings, the researchers concluded that constantly disrupting the circadian rhythm helps tumors not only survive, but also proliferate.
In a continuation of their experiments, they tried to administer a cancer drug, PD-0332991, to the mice and rats at different times of the day to see if it would be more effective if it followed the body's circadian rhythm. They found that the cancer treatment was more effective when given in the morning than at night. Not only that, but when they messed with the circadian rhythms of the mice and rats, the treatment lost some of its potency. This means that timing the administration of treatment or "chronotherapy" is just as important in the fight against cancer.
In concluding their studies, the researchers stated that "better understanding the molecular effects of jet lag, shift work, and other sources of chronic disruption may lead to strategies to minimize the increased cancer risk associated with these behaviors." So, sleep at the right time. Delaying it is only going to cause you harm.
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