Brain fog and cognitive symptoms

Cognitive difficulties are common in Long Covid and are often described as “brain fog”. People report different patterns, but it can feel like your thinking is slower, harder work, or less reliable than it was before.

Brain fog can include:

  • problems with short-term memory (forgetting what you were doing or what someone just said)

  • reduced concentration (finding it hard to read, follow a conversation, or stay on task)

  • slower processing (needing more time to think or respond)

  • difficulty finding words or following complex information

  • feeling mentally “foggy”, spaced out, or easily overwhelmed

  • sensory overload (noise, light, or busy environments becoming too much)

For many people, cognitive symptoms fluctuate and can worsen after exertion, stress, poor sleep, illness, or over-stimulation.

What PEM feels like

PEM can involve a range of symptoms, such as:

  • Sudden drop in physical ability (heavy body, weakness)

  • Brain fog (slower thinking, poor concentration)

  • Pain (aches, headaches, flu-like feelings)

  • Unrefreshing sleep (sleeping but not feeling restored)

  • Dizziness or heart symptoms when upright (palpitations, feeling faint)

  • Sensory overload (light and noise feel too much)

  • Digestive symptoms (nausea, appetite changes)

  • Temperature changes (hot flushes, chills, struggling to warm up)

Not everyone who experiences PEM experiences all of these symptoms, and PEM can look different from person to person.

What can help

These are general approaches many people find helpful. You do not have to do them all, and it’s okay to start small.

    • Do one thing at a time and break tasks into small steps

    • Use practical supports (checklists, reminders, notes, calendars)

    • Keep key items in consistent places to reduce decision-making and “searching”

    • Take short, regular breaks before you feel wiped out

    • Choose low-stimulation rest (quiet, dim light, eyes closed) rather than scrolling

    • If you experience PEM, treat reading, screens, meetings and decision-making as exertion and pace them like physical activity

    • Lower sensory input where you can (quieter times, earplugs/headphones, sunglasses)

    • Ask for information in writing (agendas in advance, written follow-ups)

    • Use your best time of day for higher-demand tasks, and batch admin for lower-capacity periods

  • If brain fog reliably gets worse after mental effort (often later the same day or the next day), it may be part of PEM. In that case, “pushing through” can lead to setbacks. Pacing and energy management are often a better starting point.

RESOURCES

BMJ Practice Pointer: (useful to share with your GP/care team), C19-YRS, The ME Association

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