Researchers at the University of Pennsylvania recently reported that disrupting normal circadian rhythms promotes tumor growth. The team, which published its study (“G1/S cell cycle regulators mediate effects of circadian dysregulation on tumor growth and provide targets for timed anticancer treatment”) in PLOS, says the results provide mechanistic support for “chronotherapy,” the delivery of cancer drugs timed to the endogenous circadian rhythm.

“Circadian disruption has multiple pathological consequences, but the underlying mechanisms are largely unknown. To address such mechanisms, we subjected transformed cultured cells to chronic circadian desynchrony (CCD), mimicking a chronic jet-lag scheme, and assayed a range of cellular functions. The results indicated a specific circadian clock–dependent increase in cell proliferation,” the investigators wrote.

Disruption of circadian rhythms, whether through jet travel, shift work, or sleep disturbances, is a known risk factor for several types of cancer. In animal models, hormonally induced circadian disruption promotes tumor growth, but the underlying mechanism or mechanisms have not been clear.

circadian rhythm and cancer
“We suggest that chronic disruption of the normal circadian rhythm tips the balance between tumor-suppressive and tumor-progressive gene expression to favor tumor growth,” said Amita Sehgal, PhD, John Herr Musser professor of neurosciences, Perelman School of Medicine, University of Pennsylvania. “Better understanding of 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, and to better treatment strategies, including timing delivery of cancer therapy for maximum benefit.”

Circadian rhythm disrupters can be caused by many factors, including:

  • Shift work in one’s job schedule
  • Pregnancy and being a new parent
  • Time zone changes
  • Medications that interrupt sleep cycles
  • Changes in daily routine such as staying up late or sleeping in
  • Medical problems including Alzheimer’s or Parkinson disease
  • Mental health problems
  • Menopause
  • Any hormone changes or disruptors
  • Excessive EMF exposure

Ways to Help:

  • Try to keep a healthy sleep pattern that includes going to bed at the same/similar time each night
  • Limit screen time (TV, computer, phone) before bed
  • Use natural sleep aides if necessary
  • Learn ways to deal with stress and time management
  • Check for drug interactions and side effects
  • Schedule regular rest/nap times
  • Avoid estrogens and/or estrogen disruptors like soy and plastics
Circadian Rhythm and Cancer - 60 Second Cancer Update with Dr. Kevin Conners | Conners Clinic