TL;DR
Turn quiet afternoons into listening time
- Thousands of audiobooks, podcasts and originals
- Listen on your phone, tablet or Echo — also offline
- Cancel anytime
An analysis of more than 554,000 posts and comments from online narcolepsy and idiopathic hypersomnia communities found that people often described brain fog through memory problems, forgetfulness and difficulty concentrating. The researchers said the term appeared distinct from fatigue and sleepiness, while noting that social media posts cannot establish how common the experience is among all patients.
A social media analysis of 554,312 posts and comments from online communities for narcolepsy and idiopathic hypersomnia found that people most often connected “brain fog” with memory problems, forgetfulness and trouble concentrating, rather than using it only as another word for fatigue. The findings, presented at the Neuroscience Education Institute’s Fall Congress, suggest clinicians may need to ask about brain fog separately from sleepiness and fatigue, researchers said.
Researchers examined posts from the Reddit communities r/Narcolepsy and r/idiopathichypersomnia, as well as the Facebook group PWN4PWN, published between August 2011 and September 2025. About 85% of the material came from r/Narcolepsy. The team used semantic similarity analysis to identify words and concepts that appeared in contexts similar to “brain fog.”
Among the strongest non-synonymous associations were “tiredness,” “difficulty concentrating,” “inability to focus,” “poor memory” and “memory issues.” When researchers grouped related clinical experiences, memory impairment and impaired concentration featured prominently, alongside fatigue and forgetfulness. Terms associated with relief included “clears,” “lifted,” “lifts” and “clearing.”
The analysis also compared posts according to whether authors emphasized fatigue, sleepiness or both. The largest difference was between people whose descriptions placed similar weight on fatigue and sleepiness and those whose posts were strongly sleepiness-dominant. The balanced group more often linked brain fog to memory and focus; the very sleepiness-dominant group more often connected it with energy and motivation, sometimes describing it as “constant,” “intense” or “severe.”
Why Separate Brain Fog From Sleepiness
The findings matter because a broad label such as fatigue or daytime sleepiness may not capture the cognitive difficulties patients are describing. Memory lapses and trouble focusing can affect school, work, driving and family life, Anne Marie Morse, DO, of Geisinger Medical Center, told MedPage Today. The analysis does not measure those effects directly, but it highlights the kinds of experiences people volunteered when discussing brain fog.
Morse recommended that clinicians ask patients to explain the symptom in their own words and treat the response as a symptom in its own right, rather than automatically translating it into fatigue or sleepiness. She said those experiences can occur together and may affect how severe brain fog feels. The researchers also suggested that a stable patient vocabulary could help inform a future patient-reported outcome measure, though the analysis did not create or validate such a measure.
Products Worth Considering
Blueair Blue Pure 211i Max Air Purifier for Large Rooms
Oral-B iO Series 3 Rechargeable Electric Toothbrush for Adults, Black, 3 Modes, 2 Brush Heads and Travel Case
LEVOIT Vital 200S-P Smart Air Purifier for Large Rooms up to 1875 ft², Quiet 27 dB Operation, AHAM VERIFIDE Certified, Air Quality Monitor,
As an affiliate, we earn on qualifying purchases.
How Patient Language Was Tracked
There is no agreed definition of brain fog, Morse told MedPage Today, and she said clinical conversations can shape how patients describe symptoms. The researchers therefore examined discussions in online communities, where people used the term without being prompted in a clinical encounter.
Mentions of brain fog rose each year from 2011 through 2017, then remained at about 1% of all posts through 2025, according to the report. The researchers found subtle changes in associated language, including a shift from memory-focused descriptions toward exhaustion and tiredness between 2011–2017 and 2018–2020. They reported that the term’s meaning remained consistent from 2018 through 2025. The report also notes that a prior social listening analysis found the phrase predated COVID by at least a decade; its use grew afterward alongside research into symptoms across several conditions.
““Brain fog” is one of the most burdensome symptoms people with narcolepsy and idiopathic hypersomnia experience, but there is no agreed definition of what it means.”
— Anne Marie Morse, DO, of Geisinger Medical Center, speaking to MedPage Today
Limits of Online Community Data
The findings describe language used in selected online communities, not the prevalence of brain fog among all people with narcolepsy or idiopathic hypersomnia. The authors identified two key limits: people who post in these groups are self-selected, and the researchers could not independently verify diagnoses from social media data.
The analysis also cannot establish that memory or concentration problems are caused by a sleep disorder, determine how symptoms affect each individual, or show that all patients use “brain fog” in the same way. Its measure of word association identifies patterns in posts; it does not confirm a clinical definition or diagnostic test.
The researchers said the consistency in the term’s use over time may help inform work on a patient-reported measure of brain fog. Any such measure would need further development and evaluation; the social media analysis itself does not establish its validity. The report does not specify a timeline for that work.
For now, Morse’s clinical recommendation is to ask patients specifically what they mean by brain fog and how it affects daily activities, while also asking about fatigue and sleepiness. Whether the patterns found online hold across a broader, clinically verified patient population remains an open question.
Key Questions
What did people in the analysis mean by brain fog?
Posts most often linked it to memory impairment, forgetfulness and difficulty concentrating. Fatigue and tiredness also appeared among the associated terms.
Was brain fog described as the same thing as fatigue?
No. The researchers found that brain fog appeared as a distinct concept in the community discussions, although fatigue and sleepiness could accompany it or shape how people described it.
Which communities were included?
The analysis covered two Reddit communities, r/Narcolepsy and r/idiopathichypersomnia, and the Facebook group PWN4PWN. The posts and comments dated from August 2011 to September 2025, and 85% came from r/Narcolepsy.
Can the findings show how common brain fog is among patients?
No. The data came from self-selected online communities, and diagnoses could not be independently verified. The analysis describes discussion patterns, not population-wide prevalence.
What did the researcher recommend clinicians ask?
Morse recommended asking patients to describe brain fog in their own words and treating it as a separate symptom, rather than assuming it means fatigue or sleepiness.
Source: medpagetoday.com
