Tuesday, December 11

Campus Queries: How does stress affect your immune system?


(Hanna Rashidi/Daily Bruin contributor)

(Hanna Rashidi/Daily Bruin contributor)



Correction: The original version of this article incorrectly stated a cell kills itself when its telomeres become too short. In fact, a cell can no longer divide when its telomeres become too short.

Campus Queries is a series in which Daily Bruin readers and staff present science-related questions for UCLA professors and experts to answer.

While students may feel discouraged from going out and relaxing during finals week, taking a study break could prevent long-term damage caused by high stress levels, according to research by Rita Effros, a professor of pathology and laboratory medicine at UCLA.

“Stress is a normal part of life, and not just when you’re a student,” she said. “The important thing is not how big the stress is but how you react to it.”

Effros studies the effects of stress on telomeres, protective DNA sequences at the ends of chromosomes. Every time a cell divides, telomeres in the cell get shorter, protecting the DNA from errors in the division process. Once the telomeres get too short, the cell can no longer divide.

Effros said her research has shown that inflammation and high cortisol levels that result from stress can cause the telomeres to shorten. When the telomeres get too short, they in turn release inflammatory molecules that can inflict chronic, long-term damage on the body’s immune system, resulting in a feedback loop.

“We need inflammation to heal our bodies from various injuries, but when the factors that promote inflammation stay high in our bloodstream, that’s a problem,” she said.

When stress affects our immune system, we can become more vulnerable to disease, Effros said. In an experiment in which participants were exposed to a cold virus, participants under high-stress situations contracted the cold at a much higher rate than those who were not stressed, she said. Likewise, students who are preparing for an exam are more likely to have a negative reaction to vaccines because of their weakened immune systems.

Effros said she thinks the best way to prevent these effects is to find methods to deal with stress. She encourages students to develop their own routines to manage the stressors of daily life. The most common methods include exercise, meditation or speaking with a friend. Research shows tai chi effectively reduces stress, Effros added.

“Learning to recognize when you’re stressed is a lifelong process,” she said. “The main thing is to find a way to deal with those stressors to prevent the effects of chronic stress.”

Effros also said she encourages students to sleep more. A lack of sleep can cause the same negative physical reactions as stress. When the proteins that cause stress reactions remain at high levels in the body, they can negatively affect the heart and immune system in the long term. Both stress and sleep deprivation can cause this.

“Going to bed at the same time every day can make sure your circadian rhythm is regulated properly,” Effros said. “This has been shown to improve sleep quality and reduce the inflammation associated with a lack of sleep.”

Stress can also cause high cortisol levels, Effros said. Cortisol is a hormone that is released during the fight-or-flight response, which is triggered in high-stress activities, such as when an animal runs from a predator.

While the hormone is useful in times of crisis, cortisol can cause severe damage to multiple organ systems, as well as the immune system, when present for long periods of time. This is common during school-related events in which students experience prolonged periods of stress, like preparing for an exam.

Effros and her colleagues conducted an experiment in which they combined cortisol and immune cells in a dish, and they found that the immune cells had shorter telomeres by the end of the experiment. They concluded that high cortisol levels caused the cells to divide more quickly and weakened their response to various pathogens.

“Cortisol actually affects immune cells directly, so it’s important to control the level of stress so we don’t have chronic inflammation and chronically high cortisol levels,” she said.

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