It's the condition with two wildly inaccurate names thanks to historical happenstance:
Myalgic Encephalomyelitis (used primarily in anglophone countries with encephalomyelitis meaning brain and spinal chord inflammation -- something which does not, in fact, exist in ME/CFS)
Chronic Fatigue Syndrome (used primarily in the United States, it's about as accurate as calling influenza Acute Fatigue Syndrome)
Because nobody knows what to call it, the compromise solution has been to take the abbreviated letters and smoosh them together against a forward slash like two teenagers in a shotgun wedding. That's because nobody knows what this condition is, we just know how it makes you feel; it leaves you prostrate. Or as journalist Ed Yong put it: "it's the annihilation of possibility."
You know that moment when you feel not just tired but a distinct, qualitative ickiness that makes you go, "ugh, I feel sick, like I'm coming down with something"--that feeling? The fancy medical term for this is "malaise" and it is the sensation most people with ME/CFS experience rather than mere fatigue. Some people say it's like having a depleted battery that won't charge. Others say it's like feeling poisoned. I've felt it as both. It profoundly limits your ability to function--except not necessarily right away. Often at about the 12-72 hour mark after you have crossed some seemingly arbitrary threshold of activity, the malaise spikes. This is known as Post-Exertional Malaise (PEM). Many of the symptoms that accompany the flu--muscle and/or joint pain, sore throat, chills--either suddenly kick in or get much worse. PEM can last for days, weeks, months, years, or become your new baseline.
But wait...there's more!
Sleep does not improve the malaise and is often dysregulated. You can't stay awake during the day or get to sleep at night or sometimes even go 48 hours with no sleep at all. Or you wake after a few hours and it takes a couple more to get back to sleep--or several. Or you're conscious but remain in sleep inertia for much of the day. Or all of this happens to you (hi! that's me!). To anyone suggesting sleep hygiene or iCBT, I may have to stab you in the eye with a rusty fork. Kidding! (Mostly) Actually I'd simply ask you to show me peer-reviewed data in which these modalities have been tested specifically in patients with ME/CFS (with clearly defined PEM), what outcomes were being studied, and what were the number of patients needed to treat to achieve whatever outcome was found to be clinically-significant (good luck with that one!).
Sitting upright or standing is more difficult with ME/CFS, something known as Orthostatic Intolerance (OI). It can feel like living on a planet where gravity is much heavier than Earth. For the most severely affected, it can feel like you can never lay flat enough to escape the oppressive heaviness. Your body moves as through molasses or hardening concrete. A substantial minority will find their heart rate jumps up (postural tachycardia) or their blood pressure drops upon standing (postural hypotension) but most patients--even those confined to bed with OI--will have blood pressure or heart rate fluctuations within normal range.
Your cognition moves as through molasses too. Even if you don't spend the day in sleep inertia, your thinking can be impaired in ways similar to how fuzzy your thinking is when drunk or with the flu. Your problems with short-term memory and concentration mean that, say, when you head for the kitchen to warm up soup, you momentarily forget why you ended up in the kitchen and then get distracted while trying to remember and then eventually start again and forget again and start again etc until an hour later you finally sit down to eat. The time it takes to react to anything that requires an answer can be frustratingly, even frighteningly, slow (there's a reason I haven't driven since 2005). Many conditions have these sorts of cognitive impairments. The popular term is brain fog.
And then there are the sensory stimuli issues. Dodgy governments commonly use sensory overload as a form of torture. They put prisoners in freezing rooms with continuous bright lights along with death metal music piped in at maximum volume (among other horrors). But the threshold at which light, noise, smell and touch becomes torture for people with ME/CFS is much lower. At the severest end of the spectrum, patients must live in blacked-out rooms with noise-cancelling headphones and struggle to tolerate even a light caress. It is every bit as isolating as it sounds.
There may also be widespread pain similar to the myalgias that accompany the flu. For some of us, it is a grueling, smoldering pressure from our fascia to our bones severe enough to require pain medications. Gut pain, usually diagnosed as Irritable Bowel Syndrome (IBS), is also common, as are migraines and other types of headache.
Further reading:
ME/CFS Fact Sheets from the Science for ME forum. This is a forum started by patients from the UK and takes a rigorous, evidence-based approach to the science of ME/CFS and beyond. It can be an intimidating place. Assertions of fact will be met with a skeptical evaluation of that claim--often at length--particularly if you're bringing in, say, some beloved peer-reviewed study but are wholly unaware of clinical trial methodology and don't know that it is merely an observational study with no control group (frequent terms bandied about: "biobabble" and "quackery"). Honest questions, however, are met with cheerful, often helpful responses. I visit regularly but post infrequently. I prefer to simply absorb the knowledge of the many current and former health care providers, statisticians, geneticists, immunologists, and fellow patients who have developed significant expertise in research methodology and physiology. Years of reading this forum have been both humbling and deeply informative.
Center for Disease Control (CDC) page on ME/CFS is a thorough, standard medical information source about symptoms, diagnosis, and management. Also has a page on severe ME/CFS, which can be helpful if you need an authoritative site to explain your strange but dire symptoms that your health care provider never learned about in medical school.
What Is Myalgic Encephalomyelitis Like? This book targets health care providers and caregivers with vivid patient stories describing their experience with ME/CFS in all its gory details.
