The Science Behind What Grief Actually Does to Your Brain

On January 17 of this year, I lost the most important person in my life. After 16 years together, being there for her last breath was the most painful moment I’ve ever known.

Until then, I had no idea what grief really was. And I know now, my brain didn’t either.

In the silence that followed, the world moved on like nothing had happened. I couldn’t. The fog, the forgetfulness, the effort it took to do the smallest tasks was beyond just sadness. It was something happening deep inside my brain.

Turns out, neuroscience has a name for it. And if you’re grieving too, you’re not imagining it.

How grief affects your brain in the early days

Grief is not just a feeling. According to neurologist Dr. Lisa Shulman, it’s trauma. And your brain treats it like one.

In a webinar for the American Brain Foundation, Dr. Shulman explained that “traumatic loss is perceived as a threat to survival.” When someone you love dies, your brain activates its fight-or-flight mode, flooding your body with stress hormones, increasing your heart rate and blood pressure, and altering your immune response. You might feel foggy, disoriented, or panicked even in the most ordinary situations. That’s your brain trying to protect you.

As she put it, “Grief is a normal protective process. This process is an evolutionary adaptation to promote survival in the face of emotional trauma.”

Neuroplasticity, or your brain’s ability to rewire itself, kicks in. But the rewiring isn’t instant. In fact, the stress of grief can create new neural pathways that hardwire fear, disrupt memory and decision-making, and slow information processing. It’s not weakness. It’s literally your brain adapting to survive.

Why your brain can’t let go after someone dies

One of the most profound explanations of grief comes from Mary-Frances O’Connor, PhD, author of The Grieving Brain. As she told NPR, “Grieving is a form of learning. Learning how to be in the world without someone we love in it.”

O’Connor, who runs the GLASS Lab at the University of Arizona, studies how our brains process loss. She says that when we bond with someone, the brain encodes that connection physically. “Even after a loved one has died, they are still physically with us,” she explained to the American Psychological Association. “They are still in those folded proteins and neural connections.”

So when people say, “I feel like I lost a part of myself,” it’s not a metaphor. The brain encodes the “we” just as much as the “you” and “me.” When the other person is gone, your brain has to relearn everything—your identity, your routines, your place in the world. And that takes time, repetition, and experience.

How grief affects your brain’s predictions, and why the world feels surreal

One of the hardest parts of grief is that your brain keeps predicting your person is still around. This is because, as O’Connor explained in Scientific American, the attachment circuits in your brain are built on the belief that the person you love will always return.

So yes, it’s completely normal to think you saw them in the street. Or to still pick up their favorite snack at the store. “The brain has difficulty learning to predict their absence,” she said. “It takes many, many days of being in the world without our spouse or our child or our best friend for the brain to create new connections.”

She compares it to a rat who expects a blue tower in its enclosure because it’s always been there. Even after the tower is gone, the rat’s brain still fires neurons as if it’s there. Our brains do the same with people.

Prolonged grief and its impact on your health

Most of us adapt, eventually. But some people get stuck.

Roughly 10% of bereaved people experience something called prolonged grief disorder, recently recognized by the DSM-5. According to Dr. O’Connor’s interview with the APA, it’s when the pain doesn’t ease and “this person has not been able to function day to day the way that they wish that they could.”

Prolonged grief doesn’t just affect your emotions. It can affect your physical health. The American Heart Association reported that people over 60 had double the risk of stroke or heart attack within 30 days of losing a partner. Researchers have also linked grief to disrupted sleep, immune system changes, and even blood clots.

And if you’re feeling panicky or foggy? That’s common, too. “At times she felt disoriented, confused, in a fog,” Dr. Shulman said of her own grief after losing her husband. These are the brain’s ways of shielding you from emotional pain.

How grief affects your brain differently from depression

There’s a reason grief doesn’t respond to antidepressants the way depression does.

O’Connor explained that while depression is often about global feelings, like regret, hopelessness, and self-blame, grief is about one thing: yearning. It’s about one person, and the brain’s refusal to accept their absence.

Grief is encoded in the reward system of the brain, the same circuits that light up when we experience love and bonding. That’s what researchers found in early neuroimaging studies. When people with complicated grief saw photos of their loved one, the nucleus accumbens, the brain’s reward center, lit up.

It’s not just a stressor. It’s the loss of something that once brought you joy. And the brain holds onto that connection.

So, how do you heal a grieving brain?

The good news: your brain is capable of healing. But it takes effort, experience, and patience.

Dr. Shulman emphasized that chronic stress rewires your brain, but that rewiring can be undone. Mindfulness, journaling, creative practices, therapy, and even just being with others help build new neural pathways. These tools let your brain know it’s safe again.

One of the most comforting things she said: “If we don’t work through the traumatic experiences that we have, they will continue to be an obstacle in our lives.”

That doesn’t mean “moving on.” It means learning to live differently. According to Dr. O’Connor, “Eventually, grief can evolve to a place where it resides mostly in the background, with only occasional periods of stronger, noticeable thoughts and feelings about the person who died.”

Grief is the cost of love, and your brain knows it

There’s something poetic about what neuroscience teaches us: grief, in all its pain, is a sign of how deeply we’ve loved.

As Dr. Katherine Shear of Columbia University told the American Heart Association, grief is “the form that love takes when someone we love dies.”

Your brain may be reeling. Your body may be tired. But you’re not broken. You’re learning. You’re adapting. And even in the fog, your brain is doing its best to help you survive the unthinkable.

You’re not alone. And you’re not imagining it. Grief changes your brain because love did too.