If you’ve ever met someone who constantly carries a water bottle, squints from dry eyes, or complains of feeling tired no matter how much they sleep, they might be living with Sjögren's disease. This condition, often misunderstood as “just dryness,” is far more complex. It’s an autoimmune disease—meaning the body’s immune system mistakenly attacks its own tissues—and it doesn’t just cause dry skin, eyes, or mouth. It can affect the whole body, and one of its most frustrating symptoms is extreme fatigue. To understand this better, we can look at two key research papers: one exploring how Sjögren's is a systemic (whole-body) autoimmune disease, and another linking fatigue in the condition to problems with the body’s tiny “energy factories,” called mitochondria.
What Is Sjögren's Disease?
Sjögren's disease, sometimes called Sjögren's syndrome, is first and foremost an autoimmune disease. As explained in the paper Sjögren's syndrome: a systemic autoimmune disease, autoimmune diseases happen when the immune system—our body’s natural defense against germs—gets confused. Instead of fighting off viruses or bacteria, it starts attacking healthy cells and tissues. In Sjögren's, the immune system mainly targets the body’s “exocrine glands.” These are glands that release fluids to keep parts of the body moist and working properly.
You might be familiar with some exocrine glands: salivary glands in the mouth make saliva to help us chew and swallow; tear glands in the eyes make tears to keep them from drying out; and sweat glands in the skin produce sweat to cool us down and keep skin soft. In Sjögren's, the immune system attacks these glands, making them swollen and less able to do their jobs. Over time, the glands can become damaged, and their ability to produce fluids drops even more.
The Dryness: More Than Just a Nuisance
The most obvious signs of Sjögren's come from this damage to exocrine glands. People often notice dryness first in their mouth (making it hard to speak, eat, or even taste) or eyes (feeling gritty, like there’s sand in them). But as the paper on Sjögren's as a systemic disease points out, the dryness isn’t limited to these areas—skin dryness is also common, and it can be more than just uncomfortable.
Our skin needs a certain amount of moisture to stay healthy. Sweat glands play a big role in this: they release sweat, which helps keep skin soft and flexible. When Sjögren's attacks sweat glands, they can’t produce enough sweat. Without enough sweat, the skin loses its natural moisture barrier. This makes the skin feel tight, rough, or flaky. It might itch, crack, or even bleed easily, especially in dry weather. Some people find their skin is so dry that lotions or creams don’t seem to help much—because the root problem is that their sweat glands aren’t working as they should.
This skin dryness is just one part of a bigger pattern. The same immune system attack that harms sweat glands also hits salivary and tear glands, which is why dry mouth and eyes often go hand in hand with dry skin. It’s a sign that the disease is affecting multiple exocrine glands, not just one.
Fatigue: A Hidden but Debilitating Symptom
While dryness is the most visible symptom, many people with Sjögren's say fatigue—extreme tiredness that doesn’t go away with rest—is the most life-disrupting. This isn’t the kind of tiredness you feel after a long day; it’s a deep, bone-deep exhaustion that makes it hard to work, exercise, or even do simple tasks like cooking or cleaning. As noted in Mitochondrial dysfunction and fatigue in Sjögren's disease, fatigue is so common in Sjögren's that it affects nearly everyone with the condition, and it can be more troubling than the dryness itself.
So why do people with Sjögren's feel so tired? The paper on mitochondrial dysfunction offers a clue. Mitochondria are tiny structures inside our cells, often called the “powerhouses” of the cell. Their job is to turn the food we eat and the oxygen we breathe into energy—specifically, a molecule called ATP, which cells use to do their work. Every cell in the body needs ATP to function: muscle cells need it to move, brain cells need it to think, and even the cells in our exocrine glands need it to produce saliva, tears, or sweat.
In Sjögren's, something goes wrong with these mitochondria. The research suggests that the immune system’s attack and the inflammation it causes (inflammation is the body’s response to injury or attack, which can cause redness, swelling, or pain) might damage mitochondria. When mitochondria don’t work well, they can’t make enough ATP. This means cells across the body don’t get the energy they need. Over time, this energy shortage builds up, leading to that overwhelming sense of fatigue.
It’s like having a car with a broken engine. Even if the car looks fine from the outside, if the engine can’t burn fuel properly, it won’t go far—no matter how much gas you put in. In the same way, when mitochondria are damaged, the body can’t “burn” food into energy effectively, leaving a person feeling drained, even after a full night’s sleep.
It’s Not Just About Dryness: The Systemic Side
One of the most important things to understand about Sjögren's, as highlighted in Sjögren's syndrome: a systemic autoimmune disease, is that it’s not just a “dryness disease.” It’s systemic, meaning it can affect parts of the body beyond the exocrine glands. The immune system’s attack can spread to other tissues and organs, causing a range of symptoms.
For example, some people with Sjögren's develop joint pain or stiffness, similar to arthritis. Others might have problems with their lungs, making it harder to breathe, or their kidneys, which can affect how the body filters waste. In rare cases, it can even affect the nervous system, leading to numbness or tingling in the hands or feet. These symptoms show that Sjögren's is a whole-body condition, not just a collection of dryness issues.
This systemic nature is why Sjögren's is often grouped with other autoimmune diseases like lupus or rheumatoid arthritis. All of these conditions involve the immune system attacking the body, and they can cause a wide range of symptoms that vary from person to person.
Living with Sjögren's: Connecting the Pieces
Understanding the links between the immune system, exocrine gland damage, mitochondrial problems, and fatigue helps make sense of why Sjögren's can be so challenging. The dry skin, eyes, and mouth are visible signs of the immune system attacking exocrine glands. The fatigue, on the other hand, is a hidden sign of deeper issues—mitochondria struggling to produce enough energy, thanks to ongoing inflammation and immune system activity.
For someone living with Sjögren's, this means managing the condition often involves more than just treating dryness. While using moisturizers for the skin, eye drops for dry eyes, or sipping water for a dry mouth can help, addressing fatigue might require looking at ways to support mitochondrial function or reduce inflammation. Researchers are still learning exactly how to do this, but studies like the ones we’ve discussed are a step forward.
Conclusion
Sjögren's disease is a complex autoimmune condition that goes far beyond simple dryness. It’s a systemic disease where the immune system attacks the body’s own exocrine glands, leading to dry skin, eyes, and mouth, and it can affect other organs too. One of its most impactful symptoms—fatigue—seems to be linked to mitochondrial dysfunction, where the body’s “energy factories” can’t produce enough fuel for cells. By understanding these connections, we can better support those living with Sjögren's and work toward more effective treatments.
References
1. Mitochondrial dysfunction and fatigue in Sjögren's disease. PubMed.
2. Sjögren's syndrome: a systemic autoimmune disease. PubMed.
