1. In the moments after being blindsided by a breakup, your heart rate might drop, suggests research in Psychological Science that looked at people's heart rates following a social rejection they didn't see coming (researchers we spoke with said romantic rejection can definitely be considered a form of social rejection).
2. Once the shock subsides, major emotional stress sets in (What did I do wrong? Am I going to be alone forever? Is it time to start adopting cats?). That stress can ramp up your sympathetic nervous system, which also leads to rising cortisol and inflammation levels. Your sleep, digestion and immunity might also suffer (you're up all night, have no appetite and seem to be catching a cold every other day).
In very rare cases, that stress might really break your heart, in a manner of speaking. A small study in the New England Journal of Medicine found that emotional distress precipitated serious heart damage in some patients without coronary heart disease, possibly due to an exaggerated response in the sympathetic nervous system.
3. You feel like you're in physical pain. That's because the brain regions that process the pain of social rejection or loss also process physical aches, according to research in Current Directions in Psychological Science.
4. You're not thinking straight (waiting in the conference room for the weekly Thursday meeting—but it's only Tuesday), and you're being more impulsive than normal. Critical thinking skills and self-control both take a dive after a social rejection, according to research.
5. You swore you wouldn't, but you look at a picture of the two of you or scroll through their Facebook page. The areas of your brain that show increased activity when you're high or craving a drug light up in response to the image of that special someone, found research in the Journal of Neurophysiology, meaning you're still powerfully drawn to them. What it also says in that moment? Your brain still thinks you're happily in love.
But your brain is also trying to help you out. Areas that control behavioral adjustments (it's time to un-follow them) and thinking toward the future ("This feels like grim death right now, but I'm going to be fine, and no, it's nowhere near time to get cats") are also lighting up.
6. At first, the only person you're interesting in talking to is the takeout delivery person ("Hi" and "thank you" count as talking, right?). But eventually that fades, as progesterone levels rise when you start to feel lonely. That's a very good thing—researchers say the hormone can motivate you to seek out social contact.
7. Months later, even if you've moved on, you may notice more hair going down the drain than usual. Major stress, including the emotional kind, can switch your hair follicles from growth to resting mode, a state called telogen effluvium. (The thinning doesn't start until about three months after the stress began because of your hair's growth cycle). Don't worry, though—it'll grow back.
Naomi Eisenberger, PhD, Associate Professor, UCLA Department of Psychology
Geoff MacDonald, PhD, associate professor of psychology at the University of Toronto
Lucy Brown, PhD, Clinical Professor, Department of Neurology, Einstein College of Medicine
Nathan DeWall, PhD, psychologist at the University of Kentucky