The Hidden Health Risks of Lying: What Science Reveals About Dishonesty and Stress

In 2004, researchers from Cornell and Columbia Universities set out to explore how lying affects a person's health. Participants were asked a series of questions while undergoing FMRI brain scans that tracked their neurological responses. The researchers already knew which answers were true and which were lies, allowing them to compare how the brain reacted to honesty versus deception.

The results were striking: telling a lie activated conflict in the brain, triggering overactivity in areas responsible for control and regulation. While the truth is straightforward, lying creates internal stress- it’s complex, carries risk, and can lead to negative consequences. The brain, in an attempt to protect itself, enters a state of tension, trying to evaluate whether the lie is worth telling and what it might lead to.

This research inspired a fictional storyline in the novel A Well-Written Murder, featuring a character who physically cannot lie, so that every time he even considers it, he has a spasm and vomits. If we all had that reaction, the world might be a lot more honest.

Lying Raises Anxiety – Even in "Smooth Talkers"

Another study conducted at Columbia in 2009 focused on how lying affects the entire body’s anxiety response. Anxiety was measured via cortisol, a hormone released by the adrenal glands during stress. Each participant’s baseline cortisol level was measured before being asked to convince a researcher of a fabricated story. As the researcher challenged them, participants were forced to invent more lies.

What the study found was clear: even participants who appeared calm and confident while lying showed a spike in cortisol levels. These stress spikes may not be obvious outwardly, but they place a burden on the body. Chronic stress of this kind can be harmful, especially when it becomes routine- essentially placing the body in a continuous state of "high alert."

Dishonesty Disrupts the Nervous System

In 2015, researchers at Harvard discovered that lying also disrupts the autonomic nervous system, which controls involuntary functions such as heart rate, digestion, breathing, and sweating. When someone tells a lie, these systems become overstimulated.

Professor Beer Sullivan wrote: “Dishonesty puts the brain on high alert, and the pressure only increases as the lie gets bigger.”

This state of chronic tension has real consequences: Long-term stress is linked to heart disease, cognitive decline, and even shortened lifespan.

The Link Between Honesty and Long-Term Health

A 2021 study tracked 20,000 older Americans and found a clear correlation between honesty and better health. Participants who openly admitted to past dishonest behaviors- such as cheating on exams or evading taxes- also reported poorer physical health compared to those who lived more honestly.

Ironically, we know this because the more honest participants admitted they had lied in the past. The health impact wasn't about moral judgment, but about how dishonesty affects the body over time.

The Brain Gets Numb to Lying- But the Body Still Pays the Price

The awareness of lying diminishes with repetition. The first time someone tells a "small lie," the fear center in the brain shows significant activity. But as the lies get bigger and more frequent, this part of the brain becomes less reactive. Emotionally, lying starts to feel easier, but the body remains tense. Stress accumulates beneath the surface, damaging health over time.

We are taught: “Life and death are in the power of the tongue.” (Proverbs 18:21) Science, it seems, agrees.