Signs of a Sleeping Brain Could Reveal Hidden Consciousness in Coma Patients

[Chip (OP)]

📎 Click on me to view the list of attachmentsTheme: Deep IndigoMidnight DarkPink & PurpleSlate GraySolarized LightEmerald GreenCyberpunk NeonNordDraculaSunset OrangeWarm AmberOcean BreezeClassic LightCrimson DuskNo theme (plain)

ListAttBBC  |  v6.3  |  2026-08-17  |  Andrew.human & Claude.ai

#	File	Size	Downloads	Info	DL
00	SmallSpindles.jpg	156.7 KB	5529	ℹ️	⬇️
Attachment ID 3719 Filename SmallSpindles.jpg File extension jpg MIME type image/jpeg Size 156.7 KB (160506 bytes) Downloads 5529 Dimensions 642 x 273 px Uploaded by Guest Message ID 47920 Attachment type Normal attachment (0) Storage folder ID 1 Thumbnail attach ID none File hash df337d03bce6f9b04f51b6c63bd9fcf03648f30a Approved Yes
No recorded downloads yet.
01	comatose_patient_header-600x243.jpg	24.4 KB	865	ℹ️	⬇️
Attachment ID 3720 Filename comatose_patient_header-600x243.jpg File extension jpg MIME type image/jpeg Size 24.4 KB (24987 bytes) Downloads 865 Dimensions 600 x 243 px Uploaded by Guest Message ID 47920 Attachment type Normal attachment (0) Storage folder ID 1 Thumbnail attach ID none File hash 6c351e5c6455d8c7d12e575df06cb32784e896e8 Approved Yes
No recorded downloads yet.

https://www.sciencealert.com/signs-of-a-sleeping-brain-could-reveal-hidden-consciousness-in-coma-patients?utm_source=Live+Audience&utm_campaign=fc42aee27d-nature-briefing-daily-20250310&utm_medium=email&utm_term=0_b27a691814-fc42aee27d-498702756

04 March 2025

Comatose patients often have a questionable prognosis. Family and doctors are left to ask, what are the chances a loved one will awaken?

A team from Columbia University and New York-Presbyterian discovered signs of hidden consciousness can be detected using electroencephalography (EEG) scans by running tests at a more unusual time: at night, when a patient's brain might typically be asleep.

While comas are often compared to a deep sleep, unresponsive brains don't tend to go through typical wake-sleep cycles. Yet by catching signs of brain patterns called sleep spindles (Sleep spindles are bursts of neural oscillatory activity that are generated by interplay of the thalamic reticular nucleus (TRN) and other thalamic nuclei during stage 2 NREM sleep in a frequency range of ~11 to 16 Hz (usually 12–14 Hz) with a duration of 0.5 seconds or greater (usually 0.5–1.5 seconds)), researchers believe they can be confident regions of the brain that play vital roles in consciousness are still functional.

EEG scans have been used before in forming a prognosis on comatose patients, but the tests can be tricky to carry out, and the results aren't always reliable. Monitoring brains for other clues that correlate with these more difficult tests is an approach that's potentially more straightforward and even more accurate.

"We're at an exciting crossroads in neurocritical care where we know that many patients appear to be unconscious, but some are recovering without our knowledge," says Columbia University neurologist Jan Claassen.

"We're starting to lift the lid a little bit and find some signs of recovery as it's happening."

The researchers monitored electrical activity in the brains of 226 patients with acute brain damage in a number of regular overnight sessions. They also ran cognitive motor dissociation (CMD) tests on the same group: the more complex EEG-based analysis, where behaviorally unresponsive individuals are asked to respond to instructions to physically move.

Sleep spindles were identified by the researchers as predictors of whether or not someone would regain consciousness. These bursts of brain waves typically occur when conscious brains are in non-REM sleep, bouncing back and forth between areas of the thalamus in what's regarded as a process of sensory and memory consolidation.

What's more, they often appeared before signs of CMD, suggesting sleep spindles can predict recovery earlier. Further down the line, the researchers think manipulating brain waves during sleep could even improve the chances of consciousness returning.

"Spindles happen normally during sleep and they're showing some level of organization in the brain, suggesting circuits between the thalamus and cortex needed for consciousness are intact," says Claassen.

Sleep spindles weren't a fully accurate way of predicting someone coming out of a coma, but they could provide some big clues. Just over 40 percent of unresponsive patients with both well-formed sleep spindles and CMD recovered consciousness before leaving hospital, with more than three-quarters regaining neurological function within a year of the study period.

The researchers think sleep data could be combined with other related tests to detect signs of consciousness. It's an area we're making progress in: recent studies have also identified improved methods for detecting CMD, and found links between brain cell activity and consciousness.

"Families of my patients ask me all the time, will my mother wake up? How is my mother going to look in three, six, or 12 months?" says Claassen.

"Very often we cannot guide them very precisely, and it's crucial that we improve our predictions to guide their decision making."

In the patients where spindles were detected, recovery was more likely. (Carroll et al., Nature Medicine, 2025):

rubberball/Getty Images:

[smfadmin]

A pattern of brain waves that occurs during sleep might help to predict whether an unresponsive person who experienced severe brain injury will recover consciousness.

Researchers recorded the electrical activity in the brains of 226 people in a coma who had experienced recent brain injury, and homed in on a specific patterns of brain activity called sleep spindles.

They found that 28% of people who had well-defined sleep spindles recovered consciousness, compared with only 14% of those who lacked this pattern.

 “We're starting to lift the lid a little bit and find some signs of recovery as it's happening,” says neurologist and study co-author Jan Claassen.