Chronic fatigue in children. Causes and symptoms | What you need to know

19.09.2025

Children often complain of fatigue. Sometimes the reason for this is simply an attempt to avoid fulfilling obligations, although in most cases, fatigue is caused by specific causes, including illnesses, which definitely deserve attention.

Table of Contents

Insufficient sleep can be caused by going to bed late. Children need 8-10 hours of sleep a night to function properly. Frequent awakenings at night can worsen sleep quality, which can also lead to a feeling of fatigue during the day. Sleep apnea (“snoring”), or pauses between breaths, is a common cause of sleep deprivation and may be associated with enlarged tonsils and adenoids, as well as other causes.
Infections, such as the Epstein-Barr virus, usually present with general weakness and fatigue. This can last for weeks or months.
Anemia is a deficiency of red blood cells – erythrocytes. Erythrocytes provide oxygen transport to tissues. Therefore, a lack of these cells always leads to a lack of energy and a feeling of fatigue.
Hypothyroidism, or underactive thyroid. Because thyroid hormones are actively involved in the body's metabolism and energy production processes, chronic hypothyroidism can cause a constant feeling of fatigue, at any time of the day.
Chronic diseases – such as asthma and related respiratory failure – are often associated with fatigue.
Heart failure – rare congenital or acquired pathologies can be the cause of general weakness and fatigue.
Anxiety, depression, and mental health problems are also often associated with feelings of fatigue.
Medication side effects – Some medications, such as antihistamines for allergies, have side effects such as drowsiness.

Just like adults, children can experience chronic fatigue without any apparent cause. Sometimes the feeling of fatigue is so intense that it disrupts the child's usual activities.

Symptoms

Sometimes it's not easy to detect fatigue syndrome in children, but some signs are definitely worth noting:

Irritability and an irresistible desire to sleep, or problems waking up in the morning
Difficulty falling asleep or feeling tired upon waking in the morning
Dizziness when standing up after sitting for a long time
Cognitive difficulties and impaired memory processes
Frequent episodes of headache and sore throat
Pain in muscles and joints
Low academic achievement rate
Decreased general physical activity
Emotional lability and irritability

When these symptoms appear, it is necessary to find the causes.

reasons

Causes of chronic fatigue can be:

Hyperstimulation. If a child is overworked physically and mentally, fatigue naturally develops. Excessive screen time, especially when it is regular, can also cause hyperstimulation.

Hyperstimulation fatigue syndrome is typically characterized by: dizziness, attention deficit, irritability, and sleep disturbances.

Dehydration. Almost 70% of the human body is made up of water; water is an essential component for oxidative and energy processes in cells, for the transport of necessary nutrients, and for the excretion of waste products, therefore water is a necessary condition for the proper functioning of the body.

Water is lost from the body through breathing, sweating, urination, and other processes. Chronic dehydration can cause chronic fatigue, which is often accompanied by nausea, dizziness, fatigue, headaches, and other symptoms.

Malnutrition. Deficiency of essential nutrients such as iron, vitamin B12, folic acid (B9), proteins, healthy lipids – disrupts the normal metabolic status of the body. Malnutrition is caused by an unhealthy diet, infections, medications and other factors that disrupt the absorption of nutrients in the gastrointestinal tract. In addition to chronic fatigue, in such a situation, the child experiences weight loss, lethargy, deterioration of hair and skin quality, drowsiness, pallor, etc. Early detection and elimination of symptoms is vital for the normal growth and development of the teenager.
sleep disturbanceInsufficient sleep or poor sleep quality may be associated with a variety of conditions, including asthma, juvenile rheumatoid arthritis, obstructive sleep apnea (snoring), restless legs syndrome, and anemia.

Insufficient sleep and rest at night affects a child's physical and mental activity during the day, academic performance, concentration, and many other functions.

Infectious mononucleosis. General weakness and chronic fatigue are among the leading symptoms of this disease. The Epstein-Barr virus, which causes mononucleosis, belongs to the herpesvirus family. The fatigue associated with mononucleosis increases the risk of physical and cognitive developmental delays.
Congenital heart diseases. The bodies of children born with congenital heart defects tire easily, which causes chronic fatigue.
Depression In children and adolescents, it is sometimes underestimated and considered typical “teenage” behavior. However, depression affects children just as much as it does adults. Interests and desires, motivation, and apathy and indifference to environmental events disappear. Long-term depression affects the child’s daily routine, sleep and eating habits, social relationships, appetite, sleep, and may eventually manifest as general fatigue syndrome.

Depression can be caused by somatic diseases (hypothyroidism) or medications (antihistamines).

Risks and complications

Children with allergies, malnutrition, and other health problems are at increased risk of developing chronic fatigue.

Chronic fatigue causes not only physical, but also mental and behavioral disorders:

Impaired working memory
Impaired critical thinking
Decreased resistance to infections
Growth retardation
Cognitive decline

Diagnosis

To identify and/or rule out the underlying causes of chronic fatigue, it is necessary to conduct laboratory tests:

When to see a doctor?

If a child often complains of fatigue, even when he or she has just woken up, or has no obvious reason for fatigue; when this condition lasts for more than 2-3 weeks and interferes with the child's usual physical activity, it is necessary to consult a pediatrician or other specialist to identify somatic or non-somatic causes of fatigue through anamnesis and instrumental-laboratory studies.