The Pain of Grief

And 6 other body-and-brain symptoms of loss, explained by science

Grief isn’t only an emotion. It’s a whole-body adaptation to a world that’s changed — whether that loss is a person, a relationship, a role, your health, or a version of life you expected to keep.

That’s why grief can show up in places you don’t expect: your shoulders, your stomach, your sleep, your concentration — even your immune system.

What’s happening in your brain when you grieve?

From a survival perspective, loss registers as a major disruption. Your brain has to update its “map” of what’s safe, predictable, and familiar.

When you’re under threat (including perceived threat), the body leans on two key stress systems:

• The sympathetic nervous system (the “fight/flight” accelerator)

• The HPA axis (a hormone cascade that increases cortisol) 

In parallel, grief often activates brain networks involved in attachment, memory, and learning — which helps explain why your mind can keep “checking” for what (or who) is missing, and why adjustment can take time. 

This isn’t a neat, step-by-step process. Even the well-known “stages of grief” are widely misunderstood as linear when real grief rarely is. 

7 surprising symptoms of grief (and why they happen)

1) Aching, heaviness, or “full-body tension”

Stress makes muscles tense by default — it’s the body’s protective posture. Over time, that tension can feel like aching shoulders, jaw tightness, headaches, or a heavy, slumped body. 
Stress and pain also amplify each other, which can make physical discomfort feel louder during grief. 

2) Breathing that feels “off”

During stress, breathing commonly shifts toward shallow, faster, upper-chest breaths. It’s not you “doing it wrong” — it’s autonomic state.

3) Sleep disruption (or sleeping too much)

Bereavement and major loss are consistently linked with a transient phase of poorer sleep — trouble falling asleep, early waking, nightmares, or unrefreshing sleep.

Stress hormones and cognitive arousal can keep the system “on,” even when you’re exhausted. 

4) Digestive changes

When the body prioritises threat response, digestion can slow, speed up, or become more sensitive — appetite loss, comfort eating, nausea, cramps, constipation/diarrhoea.

5) More colds, flare-ups, or feeling “run down”

Cortisol and chronic stress signalling can suppress or dysregulate immune function, and bereavement is associated with changes in inflammation and immune markers in multiple studies. 

6) “Grief brain”: forgetfulness, poor focus, slowed thinking

Early grief can come with measurable changes in attention and executive function, and many people experience brain fog while the brain is processing a major update to its internal model of life.

7) Exhaustion that doesn’t match your activity level

Grief is high-load work: disrupted sleep, sustained stress physiology, and constant mental processing. Fatigue is a common, expected outcome — not a personal failure.

What can help (without trying to “fix” grief)

Think regulation, not “getting over it.” These tools aim to downshift stress physiology so grief is less physically punishing.

Breath (fastest route to calming the stress response)

• Cyclic sighing / physiological sigh (exhale-focused): research suggests structured breathing, especially cyclic sighing, can improve mood and reduce physiological arousal.
  How: inhale through the nose; top-up sip of air; long slow exhale. Repeat for ~5 minutes (or 3–5 cycles as a quick reset).

• Slow paced breathing (~6 breaths/min): evidence shows voluntary slow breathing can increase vagally-mediated HRV and support parasympathetic activity.
  How: inhale 5 seconds, exhale 5 seconds. Continue 3–5 minutes.

Mindfulness / meditation (attention + rumination relief)

Mindfulness-style meditation programs show benefits for stress-related outcomes like anxiety and distress (effects vary, but the signal is consistent).

Touch + connection (the “soothing system”)

Affectionate touch and even self-soothing touch have been shown to reduce cortisol responses after stress in experimental settings, and social support (including hugging) can buffer stress effects.

Simple options: hand-on-heart + slow exhale; a longer hug with a trusted person; sitting close to someone safe.

If symptoms feel stuck or life is shrinking

If intense grief persists and causes major impairment — especially beyond ~12 months after a bereavement in adults — it may be worth speaking to a clinician, as prolonged grief disorder is now formally recognised and treatable.

Further Reading 

Seiler, A., & Jenewein, J. (2020). The Psychobiology of Bereavement and Health. Frontiers in Psychiatry. (Frontiers)

Knowles, L. M., et al. (2019). Systematic review: bereavement and inflammation/immune markers. Psychoneuroendocrinology (via PubMed). (PubMed)

Chu, B. (2024). Physiology, Stress Reaction. StatPearls / NCBI Bookshelf. (NCBI)

Harvard Health Publishing. (2024). Understanding the stress response. (Harvard Health)

Lancel, M., et al. (2020). Sleep disturbances in bereavement: A systematic review. Sleep Medicine Reviews. (ScienceDirect)

American Psychological Association. (2018). Stress effects on the body (muscle tension). (APA)

O’Connor, M.-F. (2021). Grieving as a Form of Learning. Trends in Cognitive Sciences (PMC). (PMC)

Balban, M. Y., et al. (2023). Brief structured respiration practices enhance mood and reduce physiological arousal. Cell Reports Medicine. (PubMed)

Laborde, S., et al. (2022). Meta-analysis: voluntary slow breathing and HRV. Neuroscience & Biobehavioral Reviews. (PubMed)

Dreisoerner, A., et al. (2021). Self-soothing touch and being hugged reduce cortisol after stress. Comprehensive Psychoneuroendocrinology (PMC). (ScienceDirect)

APA (American Psychiatric Association). (2022). Prolonged Grief Disorder (DSM-5-TR patient resource). (psychiatry.org)

Cruse Bereavement Support. Five stages of grief (non-linear framing). (Cruse)