And let me just say - I know it. I don't understand it, and neither do the specialists, but I know it. Fatigue is the most common symptom of MS, and is experienced by approximately 80% of people living with MS (it is also a primary cause of early departure from the workforce).
There are a couple of theories on what causes MS fatigue: a special fatigue, referred to as lassitude, is unique to people with MS. Unique and thought provoking. One of the top theories is that the fatigue is related to the activation of the immune system: the immune system releases substances to carry messages between cells. Another theory (my favourite) is that an MS brain has to work harder to get the same tasks done as a non-MS brain (working harder means using more parts of the brain). The fatigue can manifest in two ways: a general feeling of tiredness or muscle tiredness.
So what is so "unique" about it?
- Generally occurs on a daily basis
- May occur early in the morning, even after a restful night’s sleep
- Tends to worsen as the day progresses
- Tends to be aggravated by heat and humidity
- Comes on easily and suddenly
- Is generally more severe than normal fatigue
- Is more likely to interfere with daily responsibilities
This is not say that there aren't other factors that can cause fatigue in MS. Certain medications, quality of sleep, and a need to expend more energy for simple tasks (like brushing your teeth) can also play a role. MS fatigue, much to the frustration of the MSer, can be misinterpreted as depression or a general lack of trying or laziness.
I experience both a general feeling of tiredness and muscle tiredness. Some days, it's as if my limbs are cast in concrete: every step is an effort, I'm slower moving and throw in the towel a lot sooner. More often than not, these "concrete" days are accompanied by an overall cog-fog, but cog-fog doesn't always come with "concrete". With MS, you never know what you are going to get. Or when you are going to get it, which is when I experience the worst of my MS fatigue - the fatigue that sucks me down.
As I listed above, it can come on suddenly, unexpectedly. For me, my face changes. My eyes water. I start to feel anxious and scared; scared that if I fall asleep, I won't wake up again. It's as if I'm sinking. I want my bed. I need my bed. I can't get my thoughts out clearly.
MS fatigue is a real part of MS. It's hard for us to explain, and I'm sure it's hard for you to understand.