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Q: I have been very tired for many months now. In the past, I used to be able to perform a lot of work activities during the day, and then come home and go to the gym. I was very energetic. But now, I feel tired all the time. I don’t understand it.
A: What you are experiencing is fatigue. It is also known as tiredness, lethargy, exhaustion and listlessness. Sometimes, it is a physical state. At other times, it is a mental one.

Physical and mental fatigue are different. However, they sometimes coexist in one person. If you are physically fatigued for a long period of time, you are also likely to be mentally exhausted. Just to be on the same page, fatigue is a symptom of some underlying disease or state, and may be also caused by lifestyle habits or routines. By itself, it is not a disease.

How is physical and mental fatigue different? I mean, feeling tired is feeling tired, right?
When you are suffering from physical fatigue, your muscles cannot function at normal levels of physical activity. For example, if you used to be able to run a marathon, you can’t run even 5km now without feeling tired. You can’t climb stairs or carry heavy things. Physical fatigue is also known as muscle weakness, weakness or lack of strength.

If you have mental fatigue, you are likely to feel more sleepy and you’re unable to concentrate properly.

Isn’t fatigue something normal people experience every day? Should I be worried?
Everybody feels tired occasionally from overworking and over-exercise. Sometimes, they don’t have enough sleep.

This is called temporary fatigue, and we usually know why we are tired. We rest, sleep it off, or take a holiday. Then we are all right again.

Chronic fatigue is fatigue that lasts longer and is “deeper”. It can be described as a constant state of tiredness that develops over time and saps energy and mental capacity. By the way, fatigue is not the same as sleepiness. However, it can be accompanied by sleepiness.

You mentioned that fatigue can be caused by our lifestyles or routines. What sort of lifestyles or routines?
Fatigue can be caused by:
– Excessive alcohol use or abuse.
– Caffeine consumption (yes, this makes you energetic, but it can also make you tired if you’re not used to it).
– Excessive physical activity (expect to feel tired if you have been running marathons three times a week!).
– Lack of activity (this can also make you feel tired).
– Lack of sleep.
– Medications such as antihistamines, cough and cold remedies.
– Unhealthy eating habits (if you don’t have enough carbohydrate in your diet, this can also make you feel very tired as you don’t have enough fuel to burn).

What sort of medical conditions can cause fatigue?
This kind of fatigue is more serious and you need a doctor to diagnose what’s wrong with you.
Many diseases can cause fatigue. A disease involving any organ in the body that has widespread effects can cause fatigue.

These include liver failure, cancer, chronic obstructive pulmonary disease, anaemia, chronic kidney disease, heart disease, hyperthyroidism or hypothyroidism, restless legs syndrome, chronic fatigue syndrome, obesity, diabetes and even certain medications.

The underlying disease, once found, will then be treated. If optimally treated, then the fatigue will go away or become less severe.

Are there any mental problems that can cause fatigue?
Certainly. Depression is a major cause of fatigue. If you are depressed, you can feel tired or listless all the time. When you sleep, you wake up early and don’t feel refreshed. You don’t seem to have the energy to do things, and when you do them, you don’t enjoy the things you used to enjoy. Anxiety can also be a cause for fatigue, as well as grief or bereavement and stress.

When should I visit a doctor if I have fatigue? When should I be alarmed?
If your fatigue is temporary and you know what causes it (such as being in a triathlon yesterday), then you should not worry about it but rest and sleep it off.

However, if your fatigue persists for two weeks or more despite you resting, trying to reduce stress, sleeping, and eating well, then it’s time to visit a doctor.

If your fatigue is accompanied by bleeding, vomiting, chest pains, fever, headache, shortness of breath or palpitations, seek medical help immediately. Also seek treatment immediately if you have thoughts of suicide or harming someone else.

This story was originally published in AsiaOne.com. For more stories like this, head to www.asiaone.com/women.