Definitions of "brain fog" on the internet, including "Cognitive Manifestations" in the Canadian 2003 definition of ME/CFS and "Neurocognitive Impairments" in the recent 2011 ME-ICC all describe this symptom category only in terms of mental function. However, for me these impairments, many of which could also be described subjectively as a blockage that has to be worked around, are associated with physical flu-like malaise symptoms and sensations in my head/eyes which gets worse during post-exertional exacerbations, and both together can be an accurate measurement of current capacity and health status. I guess some of this overlaps with other symptom categories, such as pain or flu-like symptoms, lack of mental vitality, and central exhaustion? I think I may experience something similar too. What do others experience and how do they manage or treat it? Does their experience of "brain fog" include feelings of grogginess and being hungover or flu-like, rather than just being cognitive dysfunction? There are many hypothesis about what induces such symptoms or what can be done to treat it, but it doesn't seem like anyone really knows for sure.