TL;DR
Get health and wellness essentials delivered free with Prime
- Fast, free delivery on millions of items
- Prime Video, Amazon Music and more included
- Member-only deals all year
A social media analysis of 554,312 posts and comments from narcolepsy and idiopathic hypersomnia communities found that people often described brain fog through memory problems and difficulty concentrating, not just fatigue. The findings were presented at the NEI Fall Congress; the researchers caution that self-selected online posts cannot establish how common these experiences are among all patients.
A social media analysis of 554,312 posts and comments from online communities for people with narcolepsy and idiopathic hypersomnia found that “brain fog” was commonly associated with memory problems, forgetfulness and difficulty concentrating, rather than being used only as another word for fatigue. Anne Marie Morse, DO, of Geisinger Medical Center and colleagues presented the findings at the Neuroscience Education Institute’s Fall Congress in Colorado Springs.
The researchers examined posts from two Reddit communities, r/Narcolepsy and r/idiopathichypersomnia, and the Facebook group PWN4PWN. The material covered August 2011 through September 2025, and 85% came from r/Narcolepsy. Using semantic analysis, the team identified words and experiences that appeared in similar contexts to “brain fog.”
Among non-synonymous terms, the strongest associations included tiredness, difficulty concentrating, inability to focus, poor memory and memory issues. A separate list of commonly associated clinical experiences included impaired memory, impaired concentration, fatigue and forgetfulness. In the broader contextual-word analysis, terms included “forgetfulness,” “memory,” “fatigue,” “drunkenness” and “dissociation.” These are patterns in online language, not clinical measurements of symptoms or their prevalence.
The analysis also compared descriptions among authors whose posts emphasized fatigue, sleepiness, or a balance of the two. People in the fatigue-and-sleepiness-balanced group tended to connect brain fog with memory and focus. Those in the very sleepiness-dominant group more often connected it with energy and motivation, and used intensity or duration words such as “constant,” “intense” and “severe.”
Why Cognitive Symptoms May Need Separate Questions
The findings suggest that asking only about tiredness or sleepiness could miss how some patients describe cognitive difficulties in daily life. Morse told MedPage Today that patients describe brain fog as affecting school, work, driving and being present with family. That account is her interpretation of the patient-community findings, rather than a measured assessment of effects in a representative group.
Morse recommended that clinicians ask patients to explain brain fog in their own words and treat the response as a symptom in its own right, while recognizing that fatigue and sleepiness may affect its severity. The analysis may also help researchers develop patient-reported measures using language patients themselves use. It does not establish that any particular measure is ready for clinical use.
Products Worth Considering
Philips Sonicare 6500 Series Rechargeable Electric Toothbrush with 2 Brush Heads, White
Withings Sleep Under-Mattress Sleep Tracking Pad
Oral-B iO5 Rechargeable Electric Toothbrush with 5 Cleaning Modes and Travel Case, White
As an affiliate, we earn on qualifying purchases.
How the Online Vocabulary Changed
The report builds on earlier social listening work described by Morse. She said that analysis found the phrase “brain fog” was used at least a decade before the COVID-19 pandemic, with use growing afterward alongside research on symptoms across conditions. The current study focused on how people in narcolepsy and idiopathic hypersomnia communities described the term without being prompted in a clinical encounter.
In this dataset, mentions of brain fog rose each year from 2011 to 2017, then stayed at approximately 1% of posts through 2025. The researchers reported a shift in associated descriptors between 2011–2017 and 2018–2020, away from memory-focused language toward exhaustion and tiredness. They said the vocabulary’s meaning was relatively consistent from 2018 through 2025. The reported percentage refers to posts in the analyzed communities, not to patients or the wider population.
““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, speaking to MedPage Today
Limits of Self-Selected Community Posts
The analysis cannot show how commonly these descriptions apply to all people with narcolepsy or idiopathic hypersomnia. The researchers acknowledged that online communities are self-selected and that their posts reflect conversational patterns, not population prevalence. Diagnoses reported in social media posts could not be independently verified from the data.
The findings also do not establish why people use particular descriptions, whether the patterns differ reliably between specific diagnoses, or how the reported language relates to formal cognitive testing. The study identifies associations in posts; it does not prove that brain fog is a distinct biological symptom or determine its causes.
From Patient Language to Research Measures
Morse said the stability of the vocabulary could be useful in developing a patient-reported outcome measure grounded in how people describe their experiences. The report does not specify a timeline for such a measure or say that one has been developed or validated. Further research would need to test whether the language patterns hold in broader, clinically characterized groups.
For now, the researchers’ practical message is to ask patients directly what they mean by brain fog rather than infer it from a sleepiness score. The analysis was presented at the NEI Fall Congress; additional details about follow-up studies or clinical implementation were not provided in the source report.
Key Questions
What did the study find people mean by “brain fog”?
In the analyzed online posts, people often associated the term with memory impairment, forgetfulness and trouble concentrating. Fatigue and tiredness also appeared, but the analysis suggests the phrase was not used only as a synonym for them.
Which sleep disorders were represented?
The posts came from communities focused on narcolepsy and idiopathic hypersomnia. Researchers could not independently verify individual users’ diagnoses from social media data.
Does the analysis show how common brain fog is among patients?
No. It describes language in self-selected online communities, where 85% of the data came from one subreddit. The reported posting patterns cannot be treated as prevalence estimates for all patients.
What did the researchers recommend clinicians do?
Morse recommended asking patients to describe brain fog in their own words and considering it separately from fatigue or sleepiness, while allowing that those symptoms may affect its severity.
Source: medpagetoday.com
