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Feeling tired after mental or physical exertion is completely natural and something that can easily be resolved with a few hours of rest or sleep.
However, some people run out of energy more easily than others due to poor nutrition, lack of physical fitness and activity, or unhealthy habits such as smoking. This form of lethargy can be addressed by fixing the diet and lifestyle.
But if healthy eating, regular exercise, and proper sleep fail to make the fatigue go away, it could be a sign of an underlying medical problem that needs to be evaluated by a healthcare provider. (1)
Medical Reasons for Feeling Tired and Fatigued
Here are some common conditions associated with severe and persistent fatigue.
Diabetes can make you feel unreasonably tired at times when your blood sugar becomes too high (often in untreated cases) or too low (when on medication), and the feeling can persist even after bringing it under control.
A drop in blood sugar can lead to fainting, which is why people with diabetes are advised to carry a pouch of glucose, sugar, or milk chocolate with them at all times.
There is no definite cause of diabetes, but risk factors include family history, obesity, and erratic eating habits.
Diabetes is clinically manifested by the lack of insulin in the body. Insulin is a hormone secreted by the pancreas and is needed to properly transfer glucose from the bloodstream into the cells. This glucose is stored inside the cells to be utilized as energy later.
Low insulin hinders this glucose uptake by the cells, which renders your body low on energy. (2)
Diabetes can be of two types:
- Type 1 diabetes is characterized by an insufficient production of insulin, which can be treated through oral medication alone.
- Type 2 diabetes occurs when the pancreas produces no insulin at all, and patients have to get their required dose of this hormone through injections.
Diabetes generally doesn’t present any symptoms until it reaches an advanced stage, by which time it can be difficult to manage and may lead to serious complications.
So, it is important to err on the side of caution and go for annual checkups, especially if you have risk factors such as a family history of diabetes, thyroid ailments, and obesity.
Anemia is a very common condition characterized by a deficiency of red blood cells (RBCs) in the body. It usually occurs when you don’t get enough iron, which is needed to make a protein called hemoglobin, which gives your blood its red color.
Hemoglobin is an essential component of RBCs and is responsible for carrying oxygen to all your vital organs to keep them working properly. A low RBC count results in an inadequate oxygen supply throughout the body, which makes it weak and lethargic. (3)
Anemia is far more prevalent among females than males due to blood loss during menstruation and childbirth. Mothers who do not keep a gap of at least one year between successive pregnancies inadvertently become anemic.
The body needs vitamin B12 to make RBCs, and a deficiency of this nutrient can also lead to a specific type of anemia called pernicious anemia. The main symptoms of this condition are pale skin, palpitations, and running out of breath due to a lack of oxygenated blood in the body.
Depression is a mood disorder that gives rise to a range of physical and emotional symptoms. It makes you forlorn, unmotivated, disinterested in things that once gave you pleasure, irritable, and tired.
Low energy levels are considered to be a major symptom of depression, along with a persistent sad mood and lack of interest for more than 8 weeks.
This condition adversely impacts certain neurotransmitters in the brain such as dopamine, which keeps you alert and pushes your body toward rewarding behaviors. Thus, depression compromises your ability to seek pleasure and dwindles your energy levels. (4)
Other stress disorders such as anxiety, post-traumatic stress disorder (PTSD), and obsessive-compulsive disorder (OCD) also cause fatigue in much the same way as depression.
4. Thyroid disorders
Hypothyroidism is a common endocrine disorder characterized by an underactive thyroid gland that is unable to secrete sufficient amounts of thyroid hormones to meet the body’s needs. These hormones are essential for a variety of important physiological functions, including metabolism or the conversion of food into energy.
A deficiency of thyroid hormones slows down your metabolism, which leads to low energy levels.
Moreover, it hinders the activity of the bone marrow, which is responsible for making RBCs that carry oxygenated blood throughout the body. A low RBC count leads to anemia, which is characterized by persistent fatigue.
An overactive thyroid gland can also trigger this problem, but less commonly so. (5)
5. Heart problem
If you often feel tired and low on energy without any obvious reason, it could be a sign of heart disease. Cardiovascular problems such as faulty heart valves or left ventricular dysfunction can make it difficult for your heart to pump fresh blood properly.
Blood carries oxygen and nutrients to the various muscles and tissues in the body to keep it active and functional. But heart problems limit the supply of oxygenated blood throughout the body.
As a result, even a little physical exertion makes you run out of steam. Plus, the extra strain on the weakened heart to pump out blood gives rise to a constant feeling of tiredness. (6)
Fatigue related to heart ailments can manifest in the following ways:
- Sudden and extreme exhaustion after doing your normal exercise routine
- Constant fatigue and heaviness in the chest even without any physical exertion
- Feeling tired by doing the bare minimum task such as making your bed
- Inability to sleep despite feeling tired
6. High blood pressure
High blood pressure is considered to be a silent killer because it generally doesn’t present any visible symptoms but can make you feel extremely tired due to lack of sleep, (7) lightheaded, weak, and out of breath.
It may also pave the way for a variety of heart conditions that lead to constant fatigue. (7) These include coronary artery disease, peripheral arterial disease, heart failure, and heart enlargement. (8)
7. Sleep apnea
Sleep apnea causes brief but recurrent lapses in breathing during sleep, which keep your body from going into deep slumber.
This happens because the muscles in your mouth and throat tend to loosen up as you doze off and thereby block the upper airway. As the oxygen supply gets cut off, your brain enters into panic mode and jolts your body awake to resume breathing.
Sleep apnea mostly affects individuals with obesity who have excessive soft tissue in the upper airway and older adults whose respiratory muscles have weakened over time.
The inability to get good-quality sleep regularly on account of this condition can seriously wear you out. Your body needs proper sleep to repair and rejuvenate itself, but sleep apnea comes in the way of that and leaves you feeling fatigued throughout the day even without any exertion. (9)
8. Chronic fatigue syndrome
Chronic fatigue syndrome, or myalgic encephalomyelitis, is an idiopathic condition that makes you feel severely exhausted all the time for no discernible reason. This kind of constant fatigue does not go away with rest and is exacerbated by physical or mental exertion.
This disorder affects people across all ages, races, and socioeconomic groups but is found to be three to four times more prevalent among women than men. (10)
Patients tend to experience a significant decline in their professional, personal, academic, and social activities over time.
Less common causes
Some lesser known conditions associated with severe and persistent fatigue include:
1. Glandular fever
Glandular fever, also referred to as infectious mononucleosis, or “mono,” is a viral infection that is largely prevalent in young adults. It usually causes a high fever, swollen glands in the neck, sore throat, and severe tiredness.
Some patients may even experience a decline in RBCs, causing anemia, which further adds to the fatigue. (11)
2. Multiple sclerosis
Multiple sclerosis (MS) is a chronic autoimmune disease that affects the central nervous system.
In this condition, the body’s immune system attacks the myelin sheath, which is a protective layer that surrounds the nerves in the brain and spinal cord. Myelin insulates the nerve fibers to facilitate quick and efficient transmission of electrical impulses.
The degeneration of this fatty membrane gives rise to a series of debilitating symptoms, including severe fatigue, which is reported by most patients with MS. (12)
3. Liver disease and kidney disease
Constant fatigue is a major symptom of liver diseases, which can significantly hamper the patient’s productivity and overall quality of life. It can be attributed to certain modifications in the neurotransmission in the brain. (13)
Acute kidney failure and chronic kidney failure can also lead to extreme fatigue. (14)
Self-Care Tips According to Experts
Here are some things that can help overcome fatigue:
1. Stay active
Regular exercise helps boost your energy levels to overcome chronic fatigue.
You should start slow with short 15-minute walks or other lightweight activities and then gradually increase the intensity and duration of exercise. The ultimate goal is to get 2 hours and 30 minutes of moderate-intensity aerobic exercise weekly.
2. Maintain a healthy weight
Being overweight puts an extra strain on your body as well as your heart, causing low energy and constant tiredness. Thus, it is important to shed the extra pounds through healthy eating and exercise to feel more energetic.
3. Sleep well
Your body needs sleep to rest and rejuvenate itself, or else it will become totally worn out. According to the Royal College of Psychiatrists, one should get 7–8 hours of nightly sleep to stay in the best of health.
4. Go for talking therapy
Seek counseling or cognitive behavioral therapy (CBT) to address chronic fatigue caused by stress, depression, and anxiety.
5. Stay hydrated
Unexplained fatigue can sometimes be the result of mild dehydration. Thus, it is important to maintain proper fluid intake throughout the day. Whenever you are feeling tired for no reason, drink a glass of water to see if your condition improves before trying something else.
When to See a Doctor
If you keep feeling tired for two or more weeks despite proper rest and self-care, it’s time to see a doctor to get a proper diagnosis.
Emergency care is needed if your fatigue is accompanied by any of the following symptoms:
- Thoughts of self-harm or suicide
- Concern that you may harm someone else
- Chest pain
- Severe headache
- Irregular or fast heartbeat
- Lightheadedness or fainting spells
- Severe pain in the abdomen, pelvis, or back
- Rectal bleeding
- Vomiting or coughing blood
The medical conditions listed in this article are some of the leading causes of unexplained and persistent fatigue, but they are not the only ones. The low energy and tiredness could stem from a variety of other factors. Only when you know the root cause of the problem will you be able to treat it properly.
The healthy dietary and lifestyle changes that are routinely recommended for boosting energy levels may not work to resolve the underlying health issues that are actually making you tired.
So, if you are feeling unreasonably lethargic all the time such that it has started hampering your productivity, social life, and day-to-day activities, make an appointment with a healthcare provider. They will carefully review your medical history and symptoms, perform a physical exam, and order blood tests, if needed, to pin the culprit.
The diagnosis will determine the best treatment for your particular case. This is important not only to get rid of the tiredness but also to address the condition causing it, which may get worse and cause complications if left untreated.