What Does Loneliness Do to the Brain?
Mental HealthLoneliness

How Does Loneliness Affect the Brain?

How Does Loneliness Affect the Brain?
Everyday Health
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Updated on August 24, 2026
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After thousands of years of relying on each other to survive, people have adapted to feel safer and more secure when we’re not alone. There’s even growing evidence that social connection is as vital to human health as essential needs like food and water.

According to experts, feeling lonely can create real stress signals and have long-term effects on your health. Here are four big ways that loneliness can lead to changes in the brain that affect our thinking, perception, and well-being.

1. Loneliness Can Cause Strong Cravings

Research suggests that loneliness triggers neural responses in the brain similar to those seen when people are hungry and want food.

In a study published in 2020, neuroscientists had 40 healthy participants stay isolated for 10 hours, followed by 10 hours of fasting. After each 10-hour block, the neuroscientists used functional magnetic resonance imaging (fMRI) to measure brain activity and compared it with the participants’ baseline fMRI scans.

 They found that when a hungry person feels hunger and an isolated person feels loneliness, each state results in the same kind of brain activity. Experts have theorized that these cues could be the brain’s way to alert us to return to social connection.

2. Loneliness May Make Us More Hostile and Pessimistic

Feeling lonely may make us more likely to focus on the negative in a situation. One study found that loneliness created a response in the posterior lobe, an area of the brain associated with attention. This close attention may help explain why loneliness is likely to make people more focused on the self.

There’s also research suggesting that this kind of negative thinking can turn into a vicious cycle. Loneliness tends to cause negative thoughts, and more negative thoughts are correlated with more loneliness.

For some, loneliness can also lead to hostility or aggression. This hostility is a defense mechanism that lonely people employ because they fear further rejection, and it results in pushing people (and the companionship they crave) further away.

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3. Feeling Lonely May Make Us Less Likely to Trust Others

Lonely people are more alert to potential threats around them, and that may lead to higher levels of distrust in others. For a study published in 2021, researchers recruited 42 people with severe, persistent loneliness who weren’t diagnosed with serious mental health conditions and a control group of the same size.

For one task, participants were given imaginary money and were asked whether they wanted to keep it all or share with other participants. If they shared their cash, the monetary value would triple and the person they shared it with could return some of the funds; participants could earn more cash in the experiment but only if they took a chance on trusting the other players. The lonely participants shared less with others than their nonlonely counterparts. And fMRI scans showed that the lonely participants had less activity in parts of the brain associated with trust formation, too.

Furthermore, blood and saliva samples that measured levels of oxytocin (a hormone that, among other functions, plays a role in bonding and attachment to others) revealed that nonlonely participants’ mood increased during small talk, while lonely participants’ didn’t. Lonely participants were more likely to report not trusting the research assistants, and they produced less oxytocin than the control group.

4. Loneliness May Contribute to Cognitive Decline

Socialization can also be an important way to stimulate your brain. Without this stimulation, there’s evidence that you may experience a decrease in cognitive function.

Research has pointed to changes in the brain when people grapple with above-average levels of loneliness. One study followed the health trajectories of 25 polar expeditioners who lived in solitude in Antarctica for 12 months.

 The crew members experienced a decrease in their brain’s gray matter during their isolation, particularly in areas like the hippocampus and thalamus.
Another concern includes a heightened dementia risk for people who are socially isolated.

EDITORIAL SOURCES
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
Resources
  1. Bauer KL et al. What Is Social Connection in the Context of Human Need: An Interdisciplinary Literature Review. International Journal of Environmental Research and Public Health. March 1, 2025.
  2. Tomova L et al. Acute social isolation evokes midbrain craving responses similar to hunger. Nature Neuroscience. November 23, 2020.
  3. Finely AJ et al. Affective Neuroscience of Loneliness: Potential Mechanisms underlying the Association between Perceived Social Isolation, Health, and Well-Being. Journal of Psychiatry and Brain Science. December 26, 2022.
  4. Yin M et al. Exposure to loneliness cues reduces prosocial behavior: Evidence from N400 and P300. Frontiers in Psychology. April 17, 2023.
  5. Nadler S et al. The loneliness loop: Investigating the temporal interplay of loneliness, repetitive negative thinking, and affect in daily life. Journal of Behavioral and Cognitive Therapy. November 2026.
  6. Brinker V et al. Aggressive intentions after social exclusion and their association with loneliness. European Archives of Psychiatry and Clinical Neuroscience. October 29, 2022.
  7. Lieberz J et al. Loneliness and the Social Brain: How Perceived Social Isolation Impairs Human Interactions. Advanced Science. September 20, 2021.
  8. Guarnera J et al. The Impact of Loneliness and Social Isolation on Cognitive Aging: A Narrative Review. Journal of Alzheimer’s Disease Reports. June 29, 2023.
  9. Roalf D et al. Transient gray matter decline during Antarctic isolation: Roles of sleep, exercise, and cognition. Microgravity. July 11, 2025.
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Angela D. Harper, MD, is in private practice at Columbia Psychiatric Associates in South Carolina, where she provides evaluations, medication management, and psychotherapy for adul...

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