TL;DR
Get workout gear 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 found that people discussing narcolepsy and idiopathic hypersomnia often described brain fog through memory problems, forgetfulness and difficulty concentrating. The study, presented at the NEI Fall Congress, suggests patients may use the term to describe an experience distinct from fatigue or sleepiness, though 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 described through memory problems, forgetfulness and difficulty concentrating, not just tiredness. Researchers presented the findings at the Neuroscience Education Institute Fall Congress, adding patient-language evidence to questions about how the symptom is understood and assessed.
The researchers examined discussions from two Reddit communities, r/Narcolepsy and r/idiopathichypersomnia, and a Facebook group, PWN4PWN, posted between August 2011 and September 2025. About 85% of the material came from r/Narcolepsy. The analysis used semantic similarity to identify words and phrases appearing in contexts similar to “brain fog.”
Among the most closely associated terms were “tiredness,” “difficulty concentrating,” “inability to focus,” “poor memory” and “memory issues.” Other frequently linked descriptions included impaired memory, impaired concentration and forgetfulness. Words associated with relief included “clears,” “lifted,” “lifts” and “clearing.” These are patterns in how people wrote about the experience, not clinical measurements of symptoms or treatment effects.
The team also compared posts from groups characterized by different relative mentions of fatigue and sleepiness. People in a fatigue-and-sleepiness-balanced group more often connected brain fog with memory and focus. In the very sleepiness-dominant group, discussion more often involved energy and motivation, sometimes paired with severity or duration terms such as “constant,” “intense” and “severe.”
Why Patient Language Matters
The findings matter because “brain fog” is a patient-reported symptom without an agreed definition, and the analysis suggests people may use it to describe cognitive difficulties that do not map neatly onto fatigue or sleepiness. If clinicians treat the phrase as interchangeable with tiredness, they may miss what a patient means by it, including problems with memory or concentration.
Anne Marie Morse, DO, of Geisinger Medical Center, said the community discussions showed brain fog as “its own concept”, rather than simply another name for fatigue or sleepiness. The distinction could matter in appointments and research: a sleepiness score may not capture the cognitive problems patients describe in daily life, including at school, work, while driving or with family.
Morse said the consistent language could inform a future patient-reported outcome measure built around the words people use themselves. The study does not establish that such a measure has been developed or validated, but it offers a possible starting point for research into how to ask about the symptom and track it more directly.
Products Worth Considering
Fitbit Sense 2 Health and Fitness Smartwatch, Shadow Grey/Graphite
Levoit Core 400S-P Smart Air Purifier for Large Rooms
LEVOIT Vital 200S-P Smart Air Purifier for Large Rooms
As an affiliate, we earn on qualifying purchases.
How the Meaning Was Tracked
The analysis follows earlier work described by Morse, who told MedPage Today that the term “brain fog” appeared in use at least a decade before COVID-19. She said use grew afterward alongside research involving several conditions, including celiac disease and fibromyalgia. The current project focused on how people in narcolepsy and idiopathic hypersomnia communities used the phrase without being prompted in a clinical interview.
Mentions of brain fog in the analyzed communities rose each year from 2011 through 2017, then leveled off at about 1% of posts through 2025. Researchers reported a shift in descriptors between 2011–2017 and 2018–2020, away from memory-related terms and toward exhaustion and tiredness. They said the vocabulary remained relatively consistent from 2018 through 2025.
That timeline describes the posts included in this analysis, not the number or proportion of all people with these disorders who experience brain fog. The results were presented at a professional meeting; the supplied report does not describe a peer-reviewed journal publication.
““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 Discussions
The study captures what people chose to post, not a representative survey of everyone diagnosed with narcolepsy or idiopathic hypersomnia. Morse identified self-selection as a limitation: online community members may not reflect the wider patient population, and the results show conversational patterns rather than the prevalence of symptoms.
Researchers also could not independently verify participants’ clinical diagnoses from social media data. The analysis cannot establish that brain fog has one meaning for all patients, determine what causes it, or show that a particular treatment relieves it. Although the report describes a stable shared vocabulary in the posts after 2018, it does not provide evidence that the same pattern holds across clinical settings or other patient groups.
Questions for Care and Research
Morse recommended that clinicians ask patients to explain what brain fog means to them, rather than assuming it is another word for sleepiness or fatigue. Patients may experience those symptoms at the same time, she said, but asking separately could give clinicians a clearer account of memory, concentration and other reported difficulties.
For researchers, a possible next step is to test whether the language identified in online communities can support a reliable patient-reported measure. The meeting findings do not announce a completed measure or a planned trial, and the supplied report gives no timeline for further work. Broader testing would be needed to learn whether the patterns apply beyond the communities analyzed and whether they can be used consistently in clinical research.
Key Questions
What did the analysis find about brain fog?
In the posts studied, brain fog was often discussed alongside memory problems, forgetfulness and difficulty concentrating. People also linked it with tiredness, fatigue and sleepiness.
Which sleep disorders were represented?
The analysis drew from online communities focused on narcolepsy and idiopathic hypersomnia. The source describes posts from Reddit and a Facebook group; it does not establish that the findings represent everyone with those diagnoses.
Does the study prove brain fog is separate from fatigue?
No. The researchers found that participants sometimes described brain fog in ways centered on memory and focus, distinct from energy or sleepiness. This is evidence about language in online discussions, not proof of a separate biological condition.
What are the study’s main limitations?
People who post in online communities are self-selected, and researchers could not independently confirm their diagnoses. The analysis also cannot measure how common brain fog is among all people with narcolepsy or idiopathic hypersomnia.
What should patients and clinicians take from the findings?
Morse recommended asking patients to describe brain fog in their own words and not automatically treating it as a synonym for fatigue or sleepiness. The report does not provide individual medical advice or establish a treatment for the symptom.
Source: medpagetoday.com
