Fatigue

Sometimes we feel very tired. This can happen after we play hard. It can also happen if we do not sleep well.

Sometimes, this feeling stays for a long time. Doctors call this fatigue. It is more than just being sleepy.

Fatigue can make your body feel very heavy. It can feel like you have weights on your arms. It can make it hard to do your daily tasks.

Looking at screens for a long time can cause it. This can make your eyes sore or your head ache.

Many things can cause this feeling. It can happen because of a sickness. It can also happen because of how we live. It is a very big topic for doctors to study.

Fatigue is a state of having no energy for a long time. It is different from being sleepy. Sleepiness is when you feel like you might fall asleep. Fatigue is a much stronger feeling of being worn out. It can make it hard to do your normal daily tasks.

There are two main ways to think about fatigue. One way is normal tiredness. This happens after you work hard or do not sleep. The other way is medical fatigue. This is a symptom of a sickness. It can be linked to many things. These include heart disease, or problems with how the body fights germs. It can also come from mood disorders.

Doctors see many different kinds of fatigue. Some people feel it more at certain times of the day. Some feel it all the time. It can even feel like heavy weights are on your arms.

Many things can cause this feeling. Using digital screens for a long time can cause it. This is called screen fatigue. It can make your eyes sore or your head ache. Poor sleep can also cause it. Some medicines can cause fatigue as a side effect too.

Fatigue is a state of having very little energy for a long time. It is more than just feeling a bit tired after a busy day. Scientists and doctors look at fatigue in two different ways. One way is the normal tiredness we feel after hard work. The other way is medical fatigue, which is a symptom of a health condition. This kind of fatigue can make it very hard for a person to do their normal daily tasks.

There are many ways that fatigue works in the body. Physical fatigue happens when muscles get worn out from intense activity. Mental fatigue comes from using your brain for a long time. This can make it harder to think or pay attention. Some people also feel sleepiness, which is the urge to fall asleep. However, fatigue is often a much longer-term feeling than just being sleepy.

Doctors use special codes to group these different feelings. The ICD-11 is a big list used by the World Health Organization. In this list, fatigue is given the code MG22. This code covers fatigue that happens after hard work. It also covers fatigue that happens even when a person has not been active. This helps doctors understand if the fatigue is a symptom of a sickness.

Many different things can cause a person to feel this way. Using digital screens like phones or computers can cause screen fatigue. This can lead to sore eyes, headaches, or a sore neck. Poor sleep or certain medicines can also cause it. Some people feel fatigue because of diseases like diabetes or heart problems. Even things like heat or cold can change how much fatigue a person feels.

Scientists are still learning exactly how fatigue happens in the brain. One idea is that inflammation, or swelling in the body, might play a role. Inflammation can change how the brain sends signals. Another idea involves brain connectivity, which is how different parts of the brain talk to each other. When these connections change, it might lead to a lack of energy. Researchers are still studying these paths to find more answers.

Fatigue is a state of being without energy for a prolonged period. It is often used in two distinct ways. In common life, it refers to normal tiredness after activity. In medicine, fatigue is a symptom of various health conditions. It is a complex, multi-dimensional phenomenon. It affects the body's biological, cognitive, motivational, and emotional states. This can significantly impair a person's ability to function in their normal capacity.

There are different ways to classify how fatigue presents. Physical fatigue results from muscle fatigue after intense activity. Mental fatigue follows prolonged cognitive activity. This can impair a person's ability to think or pay attention. It may also manifest as sleepiness or lethargy. Sleepiness is specifically the tendency to fall asleep. Fatigue, however, is an overwhelming sense of exhaustion. While they often coexist due to sleep deprivation, they are not the same. Fatigue is generally a longer-term condition than sleepiness.

Medical fatigue has several distinguishing features. It is often unpredictable and varies in severity. It can be profound and have an extensive impact on daily living. Unlike normal tiredness, it often does not improve with rest. Some forms of fatigue show post-exertional malaise. This is a common feature in ME/CFS and Long Covid. Other types are affected by temperature changes. For example, MS fatigue can change with heat or cold. Some conditions cause flare-ups and remissions. Lupus and fibromyalgia may have flare-ups lasting a few weeks.

The timing of fatigue can also vary between different conditions. Some types, like cancer-related fatigue or rheumatoid arthritis, may be continual. Others, such as MS or Sjögren's syndrome, vary throughout the day. A 2010 study showed different patterns for these two. Sjögren's patients reported fatigue after rising, improved in mid-morning, and worsened later. Lupus patients reported lower fatigue after rising, which then increased through the day. Some people describe a physical sensation of weight. They may feel as if lead weights are attached to their limbs.

Many factors can cause or maintain fatigue. Adverse life events and sleep disturbances are common factors. Digital screen use can cause computer vision syndrome. This leads to eye fatigue, headaches, and neck or back pain. Medications can also be a cause. This includes beta blockers, certain allergy medicines, and chemotherapy. Substance use is also linked to fatigue. A 2020 Norway study found 69% of substance use disorder patients had severe fatigue. Alcohol consumption also shows a strong correlation with overall fatigue.

Fatigue is associated with many medical categories. It is a symptom in autoimmune diseases like lupus and multiple sclerosis. It appears in blood disorders such as anemia. It is also linked to endocrine diseases like diabetes and hypothyroidism. Many infectious diseases, including COVID-19 and tuberculosis, cause it. Neurological disorders like Parkinson's disease and narcolepsy are also connected. Even nutritional deficiencies in iron or vitamin B12 can lead to it. The World Health Organization uses the ICD-11 to classify these. Fatigue is categorized under the code MG22.

Scientists are still investigating the exact biological mechanisms. One major theory involves inflammation. Inflammation can distort neural chemistry and brain function. This is known as neuroinflammation. Cytokines are small proteins that modulate immune responses. They may play a causal role in fatigue. Another theory involves reduced brain connectivity. This refers to how different brain regions communicate. Studies have found correlations in people with MS and brain injuries. Research focuses on areas like the thalamus and the middle frontal cortex.