Thread by @anishmoonka

A 19-year-old in France went into a coma for 3 weeks. To her, it lasted 7 years. She gave birth to triplets, named them, and lost one shortly after birth. She woke up and asked the nurses where her children were.

Doctors see this often in intensive care. They call it ICU delirium, and it hits about 37% of patients there. For people on a breathing machine for weeks, the rate climbs to nearly 9 in 10.

The drugs that keep ICU patients unconscious push down the deepest sleep stages, where the brain normally files away the day. When the drugs ease off, all that suppressed dreaming floods back at once. Meanwhile, the brain stops double-checking reality. So the brain just builds, stacking vivid detail on vivid detail. Half an hour of dream time can feel like a whole year of life.

The grief follows her out of the coma. The brain regions that handle emotional pain are the same ones that hurt when you lose someone in waking life. Memories don’t come with a “this was real” tag. So the love a mother feels for children who never existed lives in the same place as the love for kids who did. Grief counselors handle these losses the way they would the death of an actual child, because to the brain, they are the same.

A novelist named Caroline Leavitt wrote about her own coma for Psychology Today in 2021. She said waking up felt like being “pulled violently” from one world to another. Drug-induced comas like hers leave the brain active enough to dream. In trauma comas, the brain mostly goes dark.

In Rick and Morty there’s an arcade game called Roy where you live a whole life in an afternoon. The brain runs the same game on its own. All it needs is a breathing machine and 3 weeks.

Thanks for going down this rabbit hole ❤️

Follow @anishmoonka for daily stories across science, history, psychology, culture & AI.

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Sources:

ScienceDirect overview of ICU psychosis / delirium and prevalence range across 26 studies
sciencedirect.com/topics/neurosc…

StatPearls ICU Delirium chapter (DSM-5 criteria, prevalence, mechanisms)
ncbi.nlm.nih.gov/books/NBK55928…

Frontiers Aging Neuroscience 2024 on benzodiazepine REM suppression and delirium
frontiersin.org/journals/aging…

Daily Mail interview with Clélia Verdier on the 21-day coma and 7-year dream
msn.com/en-za/news/oth…

Scientific American interview with Mary-Frances O’Connor on the grieving brain and prediction mismatch
scientificamerican.com/article/how-th…

Part 2. Up to 7 in 10 ICU patients leave the hospital with memories of being kidnapped, drowned, or tortured by the staff. None of it happened. The memories feel sharper than anything from their actual lives, and many never stop believing it really did.

The same scenes show up across thousands of patients. They wake up sure that the nurses were trying to poison them. They remember being held underwater while doctors leaned over them. One patient in a 2020 case study believed a staff member was a witch mixing potions. Another, a 53-year-old man on a ventilator for 30 days, described every dream as drowning or strangulation.

The ICU itself provides the raw material. A ventilator tube does feel like a hand at your throat. The wrist restraints that stop patients from yanking out tubes do feel like being tied down. Nurses leaning in to adjust equipment can look like attackers leaning over a body. Add the drugs and the delirium, and the threat becomes the only story the brain can tell.

Even years later, the memories stay vivid. About 20% of ICU survivors develop PTSD, and the delusional memories drive it more than the actual illness. Most patients don’t tell anyone, because saying it out loud sounds insane. Some live for years convinced their care team tried to kill them. They know rationally it didn’t happen but cannot shake the feeling.

There is a fix. It’s called an ICU diary. Family members and nurses write down what’s actually happening each day while the patient is sedated. When the patient wakes, they read what really took place. In a 2010 randomized trial of 352 patients, this single change cut new-onset PTSD from 13% to 5%.

If a loved one ever lands in intensive care for more than 3 days, ask about a diary. It costs nothing. And it saves them from a haunting they may never talk about.

Part 3. At the moment the heart stops, the brain has one last surge of activity. It lasts up to 30 seconds. The patterns look like deep thought. Doctors caught it the first time on an 87-year-old man whose brain was being monitored when he died.

The activity was a surge in gamma waves. These are the fastest brain waves the scan can pick up, and they show up when a person is thinking hard, remembering something, or paying close attention. Normally they fade as the brain shuts down. In this patient, they spiked.

It wasn’t a one-off. In 2013, a team at the University of Michigan measured the same surge in dying rats: 30 seconds of intense gamma activity after the heart stopped. A decade later, the same team checked four dying human patients. Two of them showed the same spike, with the strongest activity in a brain region linked to consciousness, vision, and the sense of self.

This may be what people are describing when they come back from cardiac arrest. Between 10 and 20% of cardiac arrest survivors report some version of a near-death experience. They describe peace, light, watching themselves from above, replaying scenes from their life, meeting people they have lost. The same themes show up across cultures and over a century of medical reports.

Other theories exist. Oxygen-starved brains can release floods of feel-good chemicals. REM dreaming can also bleed into waking consciousness as the brain fails. Nothing is settled. But the gamma surge is the only signal anyone has caught on a live brain scan.

The brain may save its most intense activity for the moment the body is dying. We can’t know what the patient was feeling in those last 30 seconds. But on the readout, the brain looked like it was thinking harder than ever.

Part 4. Some people physically act out their dreams: punching, kicking, screaming, jumping out of bed. It’s called REM sleep behavior disorder. Of patients with no other medical cause, 97% develop Parkinson’s, Lewy body dementia, or a related disease within 14 years.

Most nights, the brain locks the body down before letting it dream. During the dreaming stage, a small region in the brainstem releases chemicals that paralyze the muscles. Your eyes still move and your brain still dreams, but your arms and legs don’t follow along. In RBD, that lock fails. The brain dreams and the body acts out whatever it’s seeing.

The brainstem region that handles this lock-down is one of the first places Parkinson’s damages. The disease quietly destroys these cells for years before any tremors show up. The lock breaks down early, sometimes 10 to 20 years before the rest of the disease appears. Most patients notice it first when the dreams start showing up as movement.

The disorder affects about 1% of the general population and 2% of people over 50. The average age of onset is 61. About half of patients have no memory of the episodes. The bed partner is usually the first to notice.

The dreams themselves tend toward violence. Most patients describe being chased, attacked, or trying to defend themselves or their family. Patients yell, swear, jump out of bed, and hit at things only they can see. About 80% of people with RBD eventually injure themselves or their partner. The original 1986 case series described patients who had spent years giving themselves and their partners bruises in the middle of the night.

If your partner or parent acts out their dreams, take it seriously. It’s the strongest known early-warning sign of neurodegenerative disease. A sleep study can confirm it, sometimes 10 to 20 years before the first tremor.

Part 5. For 18 months, doctors at a Buffalo hospice asked dying patients about their dreams every day. 88% reported vivid dreams in their final weeks. The most common theme was the same across patients: meeting someone they had already lost.

The deceased loved ones were usually parents, especially mothers. Many patients reported visions of pets they had owned as children. Some described preparing to travel, packing for a journey, or being told they would be picked up soon. The dreams typically increased in frequency as death approached.

Patients found these dreams more vivid than ordinary ones. The emotional weight stayed with them after waking, sometimes for the rest of the day. 99% of patients in Christopher Kerr’s 2014 hospice study said their dreams felt real. They could distinguish them from confusion or delirium.

60% said the dreams brought comfort. About 19% described them as distressing, often when the dreams involved unresolved relationships or grief. The comforting dreams tended to ease the fear of dying. Patients often described them as visits from people they had lost.

The research has changed how hospice staff approach the dying process. Instead of dismissing the dreams as confusion or medicating them away, trained staff now ask patients about them and listen. Families who know to expect the dreams report less anxiety about what they are seeing. Kerr’s findings have been replicated in hospices in multiple countries.

The brain spends a lifetime building experience from the world outside. In the final weeks, when that input fades, it builds something else. Most often, it builds the people we have loved most.

Sources if you like to go deeper 🧵

Part 2 - ICU delirium terror dreams + post-ICU PTSD + ICU diary fix

“Releasing a Lot of Poisons from My Mind” — qualitative study with direct patient quotes on drowning, strangulation, shackling
pmc.ncbi.nlm.nih.gov/articles/PMC41…

Doig 2020, Case Reports in Critical Care — the witch-mixing-potions patient case report
pmc.ncbi.nlm.nih.gov/articles/PMC71…

Jones et al. 2010, Critical Care — RCT on ICU diaries cutting PTSD from 13% to 5%
pmc.ncbi.nlm.nih.gov/articles/PMC32…

Yamamoto et al. on ICU delirium and delusional memories (68% prevalence)
pmc.ncbi.nlm.nih.gov/articles/PMC80…

Righy 2019 meta-analysis on post-ICU PTSD prevalence at 19.83%
pubmed.ncbi.nlm.nih.gov/30797335/

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Part 3 - Gamma surge at the moment of death + NDE neuroscience

Vicente et al. 2022, Frontiers in Aging Neuroscience — the 87-year-old EEG case, primary paper
frontiersin.org/journals/aging…

Xu/Borjigin et al. 2023, PNAS — four dying patients human study
pnas.org/doi/10.1073/pn…

Borjigin et al. 2013, PNAS — original rat study showing gamma surge after cardiac arrest
pnas.org/doi/10.1073/pn…

Scientific American 2024 — accessible explainer with Borjigin and Vicente interviews
scientificamerican.com/article/surges…

Frontiers in Aging Neuroscience 2023 — review on the neurophysiology of dying
frontiersin.org/journals/aging…

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Part 4 - REM Sleep Behavior Disorder + 97% Parkinson’s prediction

Cleveland Clinic on REM Sleep Behavior Disorder — the 97% figure and clinical overview
my.clevelandclinic.org/health/disease…

Frontiers in Neurology 2020 — comprehensive neurologist’s guide to RBD
frontiersin.org/journals/neuro…

PMC3405405 — Idiopathic RBD as long-term predictor of neurodegenerative disorders
pmc.ncbi.nlm.nih.gov/articles/PMC34…

British Journal of General Practice 2022 — primary care guide on early RBD identification
ncbi.nlm.nih.gov/pmc/articles/P…

StatPearls — REM Sleep Behavior Disorder chapter with Schenck 1986 case series details
ncbi.nlm.nih.gov/sites/books/NB…

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Part 5 - Hospice end-of-life dreams + Kerr 2014 study

Kerr et al. 2014, Journal of Palliative Medicine — primary peer-reviewed source
liebertpub.com/doi/10.1089/jp…

PubMed listing for the Kerr 2014 study with full author list
pubmed.ncbi.nlm.nih.gov/24410369/

Hospice Buffalo research page with detailed findings breakdown
drchristopherkerr.com/research

ASCO Post 2024 — accessible explainer with Kerr interview
ascopost.com/issues/novembe…

Hospice News 2021 — interview with Kerr on methodology and replication
hospicenews.com/2021/02/22/hos…