StarTalk Radio – Special Edition

Episode: “What Loneliness Does To Your Brain” with Ben Rein

Host: Neil deGrasse Tyson
Guests: Ben Rein (Neuroscientist), Chuck Nice (Comic Co-host), Gary O’Reilly (Commentator)
Date: October 31, 2025

Main Theme Overview

This episode dives into the science of loneliness with neuroscientist Dr. Ben Rein, exploring how social isolation affects both brain chemistry and physical health. The conversation ranges from the emotional mechanics of loneliness versus isolation, how social interaction—or its lack—alters our neurobiology, and even the ways drugs (from SSRIs to MDMA) and pets can substitute or boost social bonds. Woven with humor and personal anecdotes, the discussion aims to distill practical advice for mitigating the growing “loneliness epidemic” in modern society.

Key Discussion Points & Insights

1. Defining Loneliness vs. Isolation

• Isolation is the objective state of being physically alone, while loneliness is the subjective feeling that social needs aren’t being met.

  • “It's possible to be surrounded by people, maybe even your best friends, and be lonely. And it's possible to be completely alone and not be lonely.” – Chuck Nice [04:12]

• Example: Astronaut Michael Collins’ experience in lunar orbit was isolation, not necessarily loneliness.

  • “I will not say that anymore. He's just isolated.” – Neil deGrasse Tyson [06:59]

2. What Happens in the Brain During Loneliness

• Humans are inherently social; isolation is stressful, triggering the release of cortisol (the stress hormone).

  • “When we are apart from our group, this sort of threat signal in the brain flips on that says, you are at risk. You are in danger.” – Ben Rein [08:12]

• Comparison: Solitary animals (like tigers) are stressed by company, not by being alone.

  • “When tigers are placed around each other, they show that response. Cortisol starts going up when they are by themselves.” – Ben Rein [09:03]

• Social interaction is inherently rewarding, mediated by oxytocin, serotonin, and dopamine—the “social reward” chemicals.

  • “When we have positive interactions, we're around others...oxytocin, serotonin, and dopamine, those three work together to create this sense of social reward.” – Ben Rein [11:15]

3. Long-Term Effects: Chronic Loneliness and Inflammation

• Chronic loneliness leads to persistently high cortisol, which paradoxically causes the body to ignore its anti-inflammatory effects, resulting in chronic inflammation and disease vulnerability.

  • “...the body's tissues have become desensitized to cortisol. And so with that, one of the body's main anti inflammation systems is out of order.” – Ben Rein [16:18]

• Study Highlight: Mice housed alone experienced worse brain damage from strokes due to higher inflammation—reversed when inflammation was blocked.

  • “Turns out the mice that were having worse strokes were living alone. Even though they were experiencing the exact same loss of blood flow, they had worse damage in the brain.” – Ben Rein [17:00]

4. Personality, Extroversion, and Happiness

• Extroverts tend to be happier and live longer, but “forced” social interaction is not healthy for introverts; everyone has a unique “social battery.”

  • “If you ask people who are extroverted to talk more with others and be more extroverted, their mood even improves.” – Ben Rein [19:34]
  • “Introverted people still benefit from socializing, but the sort of threshold...is way lower.” – Ben Rein [21:22]

• The “Big Five” personality traits include extroversion; people can self-assess social needs with personality quizzes.

  • “In my book, I have a trait extroversion scale that people can take and then sort of figure out where they land on that.” – Ben Rein [23:01]

5. Virtual vs. In-Person Social Interaction

• Virtual interactions strip away vital social cues (eye contact, body language, scent), making them less fulfilling than in-person encounters.

  • “My belief is that as we strip away this sort of texture of our interactions, we're losing a lot of the important signals that tell our brains we are interacting with a human.” – Ben Rein [31:59]

• Data show moods are improved more by real-life interaction, but any connection is better than none.

  • “People basically don't feel as good after interacting online...but they still feel better having less lifelike interactions than they do having no interaction at all.” – Ben Rein [32:04]

6. Empathy, Likability, and Group Dynamics

• Empathy is measured in the brain and modulated by feelings of in-group/out-group; propaganda and digital communication can dull empathy, facilitating hostility and even war.

  • “If you can get a person to dissociate the human so far from themselves that they see nothing in common, then those empathy areas aren't going to come online.” – Ben Rein [38:39]

• “When we are not experiencing these social cues online, there's no reason that the empathy areas in our brain should turn on. And so this could potentially explain why there's such hostility online.” – Ben Rein [39:33]

7. Drugs and the Social Brain

• Painkillers, like acetaminophen, reduce not just physical pain but empathy and “social pain”.

  • “Did you know it can also reduce your empathy for someone else's pain? ... It also reduces social pain.” – Ben Rein [41:13]

• Alcohol lowers social anxiety but impairs interpretation of social cues and can make people less considerate.

  • “Alcohol...probably actually makes us act worse because we could become less considerate of others emotions.” – Ben Rein [47:12]

• MDMA (Ecstasy) is a unique “empathogen,” making users more social and empathetic by releasing serotonin and dopamine. However, chronic use is toxic.

  • “Unlike alcohol, MDMA makes people much more social. It's pro-social. In fact, it's also been shown to increase empathy. It's one of the only drugs on the planet that's called an empathogen.” – Ben Rein [48:47]
  • “...it's not a drug that, like, there's no future for this drug to be taken, like, daily like a prescription. Because it's too toxic.” – Ben Rein [51:29]

8. Potential Solutions to Loneliness

• Medications are being studied, but a better solution is reinforcing social habits, finding new communities, or caring for pets (especially dogs, which co-evolved as social animals).

  • “If you're looking to sort of supplement some of that connection you've lost out on, a dog could actually hit that molecular mechanism.” – Ben Rein [56:57]

• Socializing is essential for health, as vital as proper sleep or diet—lack of it raises risk of mortality, dementia, cardiac disease, diabetes, and more.

  • “Those who are the most socially isolated were 50% more likely to die by any cause within that decade window.” – Ben Rein [60:07]

Notable Quotes & Memorable Moments

• "You know, humans are wired for what we're doing, the way we survive best. Which is chemically wired." – Ben Rein [09:32]
• "The absence of interaction — isolation — the neurobiological signature of that is a distinct problem from the absence of pleasure." – Ben Rein [11:59]
• "If you can find a community where you have something in common...that allows you to enter the room and meet those people and feel more comfortable." – Ben Rein [65:05]
• "Our brains have a lot of pitfalls where we happen to be very bad at estimating socializing... We almost always underestimate that we actually are better liked than we expect." – Ben Rein [65:56]
• “If we fail in an interaction and we are rejected by our tribe, there is a significant consequence associated with that.” – Ben Rein [67:41]

Timestamps for Key Segments

• Loneliness vs. Isolation: 04:12 – 07:05
• Cortisol, Stress, and Social Reward: 07:48 – 11:25
• Chronic Inflammation and Health Risks: 15:30 – 18:18
• Personality & Social Needs: 19:34 – 23:45
• Virtual vs. In-Person Interaction: 29:49 – 32:04
• Science of Likability & Empathy: 32:33 – 39:48
• Drugs & Social Brain (Painkillers, Alcohol, MDMA): 41:02 – 53:50
• Pets as Social Surrogates: 53:52 – 56:57
• Loneliness and Health Outcomes: 59:56 – 62:57
• Advice: Overcoming Loneliness & Building Social Habits: 63:07 – 68:32

Practical Takeaways

• Recognize isolation and loneliness as distinct and equally important to address.
• Actively seek and maintain social connections, in person if possible—just a brief, positive interaction (even with pets) can make a difference.
• Be aware of the “traps” of digital life—virtual interaction is no substitute for real presence.
• No drug can substitute for genuine, sustained social interaction without significant risks.
• Community and shared interest are powerful antidotes to loneliness; even joining a small group or club can be transformative.

Resources & Further Reading

• Ben Rein’s book: “Why Brains Need Friends: The Neuroscience of Social Connection”
  Accessible and jargon-free, aimed at helping the public understand the vital role of social bonds.

This episode delivers a compelling mix of science, practical wisdom, and wit on one of society's most pressing mental health issues. The advice? Despite our “socially lazy” brains and the allure of isolation, get up, get out there, and connect—your life may depend on it.

For additional insights and full context, listen to the complete episode on StarTalk Radio.