What’s actually happening in the brain?

In psychology, this phenomenon is often called the shared stress effect. When two (or more) people face a situation of heightened uncertainty or physical discomfort, their bodies can sync up on a hormonal level. Adrenaline and cortisol spike, but the most interesting part is oxytocin. Yep, the same “cuddle hormone” (or more accurately, 'social bonding' hormone) usually linked to tenderness and childbirth.

Studies have shown this clearly. In one common experimental design, participants are paired up: one group goes through a “cold pressor stress test” — holding a hand in ice water for 3 minutes — while the other just sits nearby. Afterward, researchers measure oxytocin levels in saliva. In pairs that experience the discomfort together, the hormone often rises significantly more than in those who only observe.

But it’s not just hormones. Shared stress creates a highly emotionally charged shared memory. The brain tags such events as “important,” and when you later recall them together — laughing about how you screamed on a roller coaster — it reactivates the same neural pathways. So the stress doesn’t just get “survived”; it turns into a shared story.

You don’t need to skydive

The effect works even in everyday situations:

• Moving in together — boxes, dust, lost keys. A month later, it’s “us against the world.”
• A night without power — candles, late-night talks, stories you don’t usually share.
• Waiting for an exam together — even if you’re just sitting in the hallway, adrenaline does its thing.

Researchers at the University of Toronto (2018) tested this with students. Those who prepared for an exam in pairs under time pressure rated each other as “significantly closer” a week later than those who studied alone.

What if the stress was traumatic? Here’s the catch. If the event is truly dangerous (a car accident, natural disaster), the effect can backfire — people may avoid each other because the memories hurt. That’s post-traumatic stress at work, and the brain tries to “forget” the trigger. But if the event is manageable (a ride, a game, even watching a scary movie), closeness is almost guaranteed.

How to use it (without manipulation)

Want to test chemistry with someone? Skip coffee. Suggest something with a mild adrenaline kick: ice skating, an escape room, or even cooking a complex dish under a timer. If afterward you feel like hugging and laughing — it worked.

This isn’t about seeking danger. It’s about tension + safety = closeness. The brain doesn’t care if you were surviving the jungle or just stuck in an elevator for 15 minutes. The key is — you were together.

So next time your heart pounds from another “oh no, what now” moment, look at the person beside you. Maybe it’s the start of something bigger than just survival.

References

• Buchanan, P., & Preston, S. H. (2018). The effects of shared experience on closeness. Journal of Experimental Social Psychology.