Adrenaline Doesn't Actually Cause the Fight-or-Flight Response, New Study Says

When you're overcome with fear, it's not adrenaline making you want to fight or flee. (Credit: Master1305/Shutterstock)A thrilling high when you’re faced with danger, a boost of energy when you’re going for an intense run – we tend to associate these rushes with adrenaline, a hormone synonymous with our fight-or-flight response. But it turns out adrenaline might not be what activates our brains' stress reaction after all.
In fact, our bones might be doing more work than we orig