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Why am I always tired?

Mary Van DorenVerified

Senior Editor

10 positive reviews
Counteracting fatigue, in three tips
  • Use your bed for sleep only (no work)
  • Activate endorphins by exercising
  • Run cold water over your wrists or temples

Do you sleep well every night? Millions of people complain about lack of sleep, fatigue, and feeling sleepy in the middle of the day. Sometimes it seems that no one is really getting a good night’s rest.

Dr. Charles Patrick Davis, an Emergency Medicine doctor in San Antonio, TX, says, “One of the most common complaints that I hear when taking a history from a patient of a current illness is that the patient says, almost as an afterthought '... and I don't know why I am so tired.'"

Dr. Davis stresses that while most patients aren’t seeing him because they’re tired, their fatigue is often a clue to an underlying illness. Fatigue is a lingering tiredness that’s constant and limiting, with unexplained, persistent, and relapsing exhaustion, leaving you with a lack of energy and motivation. That’s not the same as being sleepy – though you can experience both at the same time.

A tired looking woman looks out of a window
Persistent fatigue is usually rooted in either mental illness or chronic illness. According to one study, over 90 percent of people suffering from major depressive disorder complained of severe fatigue.

Fatigue is usually a symptom of something else. Of course it can be traced to common temporary causes, such as a recent bereavement, a new exercise regimen, or a few later-than-usual nights.

But if you’re always tired, the problem can usually be traced to mental health issues or illness, whether chronic or simply undiagnosed.

Mental health issues as the cause of fatigue

Depression is one of the more common causes of fatigue. It affects twice as many women as men and often runs in families, commonly beginning between the ages of 15 and 30. It can include postpartum depression after the birth of a baby or seasonal affective disorder in the winter, or be a part of bipolar disorder.

Signs of depression besides fatigue include:

  • A depressed mood most of the day
  • Lack of interest
  • Eating too much or too little
  • Over- or under-sleeping
  • Feeling hopeless and worthless

Although the specific causes of depression are unclear, these are highly treatable medical problems. Medication, psychotherapy, or a combination of the two can help relieve symptoms, including fatigue.

Fatigue can also result from anxiety or emotional stress, especially when stress progresses to the point of an anxiety disorder or a sleep-related problem.

A hand squeezes a stress ball shaped like the globe
Emotional stress is highly correlated with fatigue. It's hard for your body to sleep when it's under stress; fatigue then causes stress in a vicious, darkly ironic cycle.

According to the Anxiety and Depression Association of America (AADA), anxiety disorders are the most common mental illness in the U.S., affecting 40 million adults in the U.S. ages 18 and older (which is 18 percent of the U.S. population). The AADA states that “anxiety disorders are highly treatable, yet only about one-third of those suffering receive treatment.”

Anxiety symptoms may include:

  • Agitation
  • Difficulty sleeping
  • Excessive worrying
  • Feeling "on alert" most of the time
  • Feeling of impending doom
  • Nervousness

Anxiety disorders are caused by a complex set of risk factors including genetics, brain chemistry, diet and lifestyle habits and poor gut health. To fight anxiety, you need to improve your diet, get plenty of sleep and exercise, and avoid stimulants, including caffeine and those found in processed foods.

Illnesses that cause fatigue

Many people suffer from ongoing fatigue because of metabolism or hormonal problems. These include:

  • Thyroid disease
  • Adrenal fatigue
  • Anemia
  • Rheumatoid arthritis
  • Autoimmune diseases
  • Fibromyalgia or chronic fatigue syndrome
  • Diabetes or blood sugar imbalance
  • Cancer (along with the related chemotherapy and radiation therapy)
  • Allergies

Not everyone agrees on these causes of fatigue. While many people blame their hormonal glands, such as the adrenals or thyroid, for their tiredness, Dr. Robert Vigersky, a past president of the Endocrine Society, argues that the symptoms of supposed hormonal fatigue are very common in people in general.

A doctor examines the thyroid of a patient with chronic fatigue
Thyroid complications are commonly associated with fatigue, as the thyroid controls the production and distribution of hormones.

Dr. Vigersky believes that in many cases, fatigue is due to common problems such as poor sleep habits, poor diet, stress at work or home or depression.

A condition that is well established as a cause for fatigue is anemia, in which a person has a lower than normal level of red blood cells. This limits the amount of oxygen reaching cells and tissues throughout the body.

Anemia symptoms include:

  • Feeling like you’re always tired despite how much you sleep
  • Weak bones and muscles
  • Trouble exercising
  • Being unable to concentrate

Treatment for anemia depends on the type, cause, and severity of the condition. Treatments may include dietary changes or supplements, medicines, procedures, or surgery to treat blood loss.

A diagram of the difference between anemic and normal blood cells
Anemic patients often complain of chronic fatigue. If you experience the symptoms described above, talk to your doctor about getting a complete blood count (CBC).

JustAnswer's Dr. Manos explains that there is a common disorder that has multiple neurologic symptoms, including fatigue, thirst and frequent need to urinate, which is often undiagnosed. This is diabetes insipidus, which is unrelated to blood sugar diabetes. With this condition, the person is either not producing enough of the hormone that adjusts water being released through the kidneys, or the kidneys are not reacting to the hormone.

"Doctors overlook this problem as I have for decades," says Dr. Manos. "I find this disorder almost every week in JustAnswer customers. Find a smart internist or endocrinologist and insist to be checked for diabetes insipidus."

It’s also not unusual for sufferers of arthritis to battle continual fatigue. Unfortunately, it seems that medications used to treat inflammatory arthritis have little effect on fatigue. But unchecked inflammation and pain caused by arthritis certainly contribute to fatigue. So it’s critical to get disease activity under control in order to get your energy back.

The 80+ types of autoimmune diseases, in which the body is attacked by its own immune system, share hallmark symptoms, such as fatigue, dizziness, and low-grade fever. For many autoimmune diseases, symptoms come and go, or can be mild sometimes and severe at others.

Chronic fatigue syndrome, also known as myalgic encephalomyelitis, or ME/CFS, and fibromyalgia (FM), are not autoimmune diseases, but often have symptoms of some autoimmune diseases, such as pain and fatigue.

Symptoms of ME/CFS come and go, and this disease is commonly misunderstood by laymen. The cause is not known. FM is a disorder in which pain or tenderness is felt in multiple places all over the body. Other symptoms include fatigue, trouble sleeping, and morning stiffness. FM mainly occurs in women of childbearing age. But children, the elderly, and men are sometimes can also get it. The cause is not known.

Diabetes can directly cause fatigue with high or low blood sugar levels. Also, people with diabetes often have infections they don’t know about. Infections take energy to fight, which in turn can cause fatigue.

Common medical implements used to treat diabetes
Diabetes is another common medical condition associated with fatigue. Those with diabetes often experience low blood sugar, which manifests as lethargy or fatigue.

Cancer or cancer treatment may also cause fatigue. This type of fatigue may feel like persistent physical, emotional, and mental exhaustion. Cancer-related fatigue is different than feeling tired after not getting enough rest. It doesn’t match the person’s level of activity, and does not improve with rest.

Even the most common allergy can also be a cause of chronic fatigue. One way to reduce symptoms, including fatigue, is to take steps to avoid the offending allergen. In addition, proper medication can help with symptoms, including topical nasal steroids, non-drowsy, second-generation oral antihistamines and topical nasal antihistamines.

Allergy shots may help in severe cases. This treatment involves weekly shots of increasingly higher solutions of the offending allergens. Allergy shots take time to be effective and are usually administered over a period of three to five years.

Infections that can cause fatigue

Functional medicine specialist Dr. Jill Carnahan explains that many people who believe they have chronic fatigue syndrome (see above) are actually suffering from hidden infections, including:

  • Epstein Barr Virus (EBV)
  • Cytomegalovirus (CMV)
  • Human Herpes Virus (HHV-6)
  • Parvovirus (Parvo B19)
  • Chronic mold and mycotoxin exposure
A microscopic view of parovirus
Parovirus under the microscope. Parovirus usually affects children, and manifests as a "slapped cheek" rash with secondary symptoms like fever and diarrhea.

The initial infection followed by chronic inflammation of the immune system could explain the cause of fatigue in some genetically susceptible individuals.

In many severe viral infections, explains Just Answer Expert Dr. Muneeb Ali, the virus suppresses the production of white blood cells in the bone marrow for a few weeks, which leads to severe fatigue. "However, once the patient fights of the infection (which may take up to 4-6 weeks in some situations), the count bounces back."

More commonplace infections also cause fatigue, such as the flu. Sometimes you may only notice a disease or illness, such as glandular fever, Lyme disease or AIDS, because you have fatigue. Other infections, which have more noticeable symptoms along with fatigue, include pneumonia, hepatitis and tuberculosis.

Heart and lung problems that cause fatigue

Most people recognize the well-known symptoms of heart disease. But women, older adults, and people with diabetes may have little or no chest pain. They are more likely to have symptoms other than chest pain, including fatigue

Fatigue may be a sign of heart trouble when:

  • You feel much more tired than normal. It's common for women to feel severely tired before or during a heart attack. 
  • You feel so tired that you can't do your normal daily activities
  • You have sudden, severe weakness

If any of these signs happen to you and you think you might be having a heart attack, get immediate help.

Constant fatigue and a lack of energy are also common for individuals living with chronic obstructive pulmonary disease (COPD). Symptoms of COPD not only deplete your physical strength and energy, but can also impact your emotional health. With COPD, breathing becomes difficult and labored. COPD reduces airflow in and out of the lungs, therefore reducing the air supply for the whole body.

A being tested for CPOD after suffering from chronic fatigue
COPD, or chronic obstructive pulmonary disease, can lead to fatigue. Here, a patient undergoes a spirometry test common in diagnosing COPD.

Without an adequate amount of oxygen, your body will feel exhausted. Many of those with COPD are all too familiar with the associated fatigue that comes along with the disease. However, there are steps that you can take to fight it.

Fatigue and COPD work together in a vicious cycle. When feeling lethargic because of a lack of oxygen, people are more likely to avoid physical activity. Because they avoid activity, they lose their stamina and grow tired more easily. Tips for combatting the fatigue of COPD can be found here.

Fatigue as a side effect, not a symptom

Fatigue can develop as the side effect of many situations, lifestyles or behaviors, and disorders. Irregular sleep hours, too little sleep, and even sleep apnea – a condition in which a person's breathing is interrupted during sleep – often cause fatigue.

While lifestyle changes will improve fatigue problems resulting from bad sleep habits, people with untreated sleep apnea actually stop breathing repeatedly during their sleep, sometimes hundreds of times, leaving the brain the body without enough oxygen.

Lifestyle changes such as losing weight, avoiding alcohol before going to bed, and changing sleeping positions can help with mild apnea. For more serious cases, a continuous positive airway pressure (CPAP) machine, which delivers a continuous flow of air into the nose to help keep the airways open, is the most common treatment for sleep apnea.

Fatigue is also a side effect of many lifestyle problems, such as poor diet, lack of iron I the diet, sedentary lifestyle, drinking alcohol or checking email just before going to bed, working through vacations, or drinking caffeine all day. Even dehydration, from not drinking enough water daily, can cause fatigue by lowering blood volume. As JustAnswer Expert Dr. Ted Manus explains, "The body can't function when blood volume decreases and your circulation has to cut corners so you don't stand and then fall down."

Fatigue created by medications

Many common medications also have fatigue as a side effect. These include:

  • Blood pressure medications
  • Statins and fibrates
  • Proton pump inhibitors
  • Benzodiazepines / anti-anxiety medications
  • Antihistamines
  • Antidepressants
  • Antibiotics
  • Diuretics

If you’re taking any of these, check with your doctor about any fatigue you’re experiencing.

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