Chronic jet lag found to increase tumor growth and affect immune response

Disrupting the inner circadian clock can have wide-reaching effects on the body, and now a new study conducted by researchers from Virginia Tech has explored how frequently experiencing jet lag can negatively affect consumers’ health. In a study conducted on mice, they found that chronic jet lag makes tumor growth more likely, and can also have a negative effect on the body’s overall immune response. 

“We combined two different approaches of chronobiology research to study the effects of circadian desynchronization on both tumor growth and immune rhythms, and we found a link,” said researcher Diego Golombek. 

“You need optimal rhythms in immune cells and immune humoral factors to quell rapid tumor growth. When circadian rhythms are chronically disrupted, these rhythms are impaired, inverted, or disappear entirely, which could help explain why the tumors were significantly larger in the desynchronized group.” 

The power of the body’s inner clock

The researchers injected mice with melanoma cells and then divided them into groups: one group experienced 12 hours of daylight and 12 hours of darkness while the other group’s daylight and nighttime hours shifted drastically every two days of the study. This mimicked the effects of consistent jet lag and allowed the researchers to assess how manipulating the body’s internal clock affected health outcomes. 

Ultimately, the team found that not giving the body the chance to adjust to a new time zone can lead to serious health complications. In just one month, the researchers learned that the body’s overall immune response was compromised, and even immune cells in organs that weren’t associated with the tumor weren’t operating as they normally would. 

This change to the mice’s immune systems also affected the way the tumor progressed, as tumors grew three times faster for the group that experienced chronic jet lag. The immune cells surrounding the tumor were also altered in the jet lag group; the researchers said the inconsistent internal clock created a better environment for the tumor to grow. 

While the researchers plan to do more work on the connection between circadian rhythms and cancer progression, they hope that these findings highlight how detrimental chronic jet lag can be to overall health. 

“A key takeaway from this study is that if someone has a proliferative disorder, in this case melanoma, doing shift work or regularly changing time zones could exacerbate the problem by dampening immune system response to tumor growth,” said researcher Carla Finkelstein. “This research also helps explain why some tumors win the race when a person is exposed to the chronically stressful conditions that occur when the environment and the body’s clocks are misaligned.”