What is fatigue?

Fatigue is a cipher of a word. Anyone who has parented a newborn knows intense sleep deprivation. Athletes know physical exhaustion. College, medical, and architecture students know cognitive overload combined with stress. Anyone who has stayed up too late and then had to get up and start their day as normal knows the feeling of having to push their body through heavy air. And any of these people might use the word fatigue to describe their situation. So the name Chronic Fatigue Syndrome (CFS), which the CDC coined in 1988, leads to a false sense of understanding. No one knows what it means…because everyone thinks they know what it means. In my first year of being sick, I was at a gathering and someone who knew I was dealing with a significant illness asked me how I was. I told her that today was a good day. I woke up and actually felt like getting up. Her response was “Yeah, I know what you mean. I never want to get up in the morning.”  I don’t remember if I responded to her, or if I just wish in hindsight that I’d responded to her, but in my “memory” of the exchange I say, “You have a hard time getting up in the morning after a year of sleeping 13-16 hours every night?”  Yeah. NOT the same thing. I have clear differentiations in my world between tired, sleepy, exhausted, and fatigued, but we don’t live in that world. Most people don’t have any idea about what the medical use of “fatigue” means; but then, neither do most doctors. 

Things are getting better. The pandemic and widespread acceptance of the debilitating nature of Long Covid mean that the medical world, and to some extent the general public, are getting better at acknowledging the fact that my fatigue and yours are not the same thing. But it is still rough. After I relapsed in 2021 I found a new Integrative Health Clinic where I started receiving care. The medical director of the clinic is a truly magnificent person and doctor. I can write pages about how he has cared for my body, mind, and spirit with respect and skill. He was able to identify many of the underlying mechanisms and systems that need support, but he was not an expert in CFS per se.  On one visit, he asked how my fatigue was. He said, “Rate your energy on a scale of 1 to 10 where 10 is you feel like Usain Bolt and 1 is you just lie around and watch Netflix all day”. Because I like and respect him so much I pretty quickly told him that his scale is off. Only watching Netflix is on the lower end of my scale but it is distinctly NOT the bottom of it. And the top of my scale is being able to function physically and cognitively in the world for 10+ hours, NOT exercising like a professional athlete. He’s among the best doctors for CFS I’ve had in 10 years, and he still does not understand what fatigue is in my world.

So let me share how I define several related terms:

Tired: a normal, healthy response to exertion. After a soccer game, you are tired. After taking final exams in school you are tired. To recover you need rest. This happens to all people, even when healthy.

Sleepy: the experience of needing to go to sleep. Your daily circadian rhythms ebb and flow based on the time of day and when you last slept. The longer since you last slept the stronger your need to sleep grows. Also, if you have had insufficient or ineffective sleep you feel sleepy. To recover you need…sleep. Again, an experience of healthy people.

Exhausted: an extreme version of either being tired or sleepy. Or maybe both at the same time. Also, something experienced by the healthy.

Fatigued: a medical symptom from an illness. People with illnesses that cause fatigue describe feeling drugged, heavy, leaden, empty, and depleted. There is a decreased capacity for creating energy, not just a temporarily empty tank. With ME/CFS and many other chronic illnesses, the mitochondria are compromised. Mitochondria are the organelles in every cell in your body that turn sugar into ATP (the molecule that moves energy around in our bodies); so the very mechanism to create energy is malfunctioning in each cell in the body.

Again, the problem arises when people use the word fatigue as a synonym for, or even a milder version of tired, sleepy, or exhausted. “How are you today?”  “Oh, I’m okay; just a little fatigued from a big push at work.”

Resting with my cat Gabby

Here’s the fatigue scale I developed to log energy/fatigue variations within and across my days. (My doctor used an energy scale where higher is more energy. I use a fatigue scale where higher is LESS energy.)

1: Feel bright, clear, and energetic physically/mentally for 10+ hrs. Can work and exercise with delight. (Notice that I might still be in bed 12 hours a day, but the time I’m up is not limited by fatigue.)

2: Can be physically and cognitively active for 7-10 hours and feel great

3: Can be physically and cognitively active for 4-7 hours and feel good

4: Can be out of the house or doing cognitive work for 2-4 hrs and feel good

5: Can do 1-3 outings and feel mostly ok while doing them. This level of exertion may cause PEM (post-exertional malaise) the next day.

6: Can do trips outside the house but it's hard; these trips likely cause PEM.

7: Can be up in the house and do things like cook periodically. Need to rest in between. Can not safely drive a car. Walking in the house causes PEM.

8: Can read and watch Netflix while lying down, but nothing else. Being up in the house takes effort. Standing causes PEM.

9: Reading or watching Netflix is overwhelming. I can play online cards. Can’t focus enough to read any text. I limit trips to the kitchen or bathroom because it is so hard. Siting up causes PEM.

10: Unable to get out of bed. Others have to bring me food in bed. Getting to the bathroom is extremely hard. I lie in bed, and rolling over feels like exertion. Feel drugged most of the day. My mind is blank.

These are MY definitions and scales.  Every person with CFS or Long Covid experiences fatigue uniquely. Still, the difference between our illness-caused fatigue and a healthy person’s exhaustion is important to delineate.  Because our understanding of fatigue is not nuanced, our language is not specific; but the experience is profound.

How do you describe fatigue to those who don’t understand it?