The silent signal in the body: Almost everyone feels tired sometimes, after a short night, a busy week, a viral illness, a stressful period, or family overload. But there is a different kind of fatigue, a fatigue that is not resolved by sleep, does not improve over the weekend, and causes difficulty waking up in the morning, concentrating at work, exercising, or even performing simple tasks. When this fatigue persists, it is no longer just "modern life". It is a sign that it is time to stop and check.
Fatigue is one of the most frequent reasons for visiting family doctors, and it can stem from lifestyle, mental state, physical illness, or medications. The accepted medical evaluation begins with the clinical history: When the fatigue started, whether it appeared all at once or gradually, if it worsens during the day, if sleep is refreshing, if there is weight loss, fever, pain, shortness of breath, heart palpitations, low mood, or a change in appetite. In many cases, sophisticated tests are not needed at the outset, but rather an organized inquiry, a physical examination, and basic blood tests guided by the resulting clinical picture.
The first reason worth considering is anemia or iron deficiency. Many people are familiar with the word "hemoglobin", but do not always understand that low iron stores can also cause fatigue even before clear anemia appears. The body needs iron to produce red blood cells and to transport oxygen to tissues. When there is a deficiency, a person may feel weakness, fatigue upon exertion, a rapid heart rate, mild shortness of breath, dizziness, headaches, or decreased concentration. In women of childbearing age, the cause can be significant menstrual bleeding; in men and postmenopausal women, blood loss from the digestive system must also be investigated; and at any age, diet, absorption, medications, and underlying diseases should be checked.
The second reason is the thyroid gland. Hypothyroidism slows down many processes in the body and can cause fatigue, sensitivity to cold, constipation, weight gain, dry skin, hair loss, a slow heart rate, low mood, and a general feeling of heaviness. Sometimes the picture is very subtle: The person simply feels that they are "not themselves". Conversely, an overactive thyroid can also cause fatigue, but through a different mechanism: A rapid heart rate, tremors, weight loss, sweating, nervousness, and poor sleep. A relatively simple blood test can help identify the direction.
The third reason, which is frequently missed, is poor quality sleep. It is not enough to ask "how many hours did you sleep", but also "how did you sleep". A person can lie in bed for 8 hours and still wake up exhausted if they suffer from sleep apnea, severe snoring, multiple awakenings, pain, restless legs, nocturnal reflux, or from the use of alcohol and medications that impair sleep quality. Sleep apnea is more common in people with excess weight, a wide neck, snoring, awakenings with a choking sensation, dry mouth in the morning, morning headaches, and daytime sleepiness. It does not only cause fatigue, but is also linked to an increased risk of high blood pressure, arrhythmias, and traffic accidents.
The fourth reason is depression, anxiety, and prolonged stress. Many imagine depression as prominent sadness, but sometimes it appears as fatigue, heaviness, decreased energy, lack of motivation, unrefreshing sleep, difficulty concentrating, or a sense of burnout. Prolonged anxiety can drain the body through constant alertness, an increased heart rate, muscle tension, and fragmented sleep. Chronic stress is not just "in the head". It activates hormonal and nervous systems that affect sleep, appetite, the digestive system, pain, and the ability to recover. In such cases, blood tests may be completely normal, but the person is still truly suffering.
The fifth reason is nutritional deficiencies. Beyond iron, a deficiency in vitamin B12, folic acid, or vitamin D can also be linked to fatigue, weakness, muscle aches, numbness, decreased concentration, or a general low feeling. It is important to be cautious of exaggerated interpretation: Not every slightly low value explains severe fatigue, and not all fatigue is solved with a supplement. But when there is a restricted diet, veganism, weight loss, digestive system surgeries, bowel diseases, prolonged use of certain medications, or accompanying symptoms, there is certainly room to check.
The sixth reason is medications and substances that appear innocent. Certain medications for blood pressure, anti-allergy drugs, sleep medications, some psychiatric medications, pain relievers, anti-epilepsy drugs, alcohol, and cannabis can cause fatigue, drowsiness, or decreased alertness. Sometimes the medication does not "put you to sleep" immediately, but rather creates a continuous feeling of heaviness. Therefore, one of the important questions in investigating fatigue is not only what diseases a person has, but what they take every day, including supplements, over-the-counter medications, and drops or pills that seem insignificant. Fatigue can also be related to medications or depression, and sometimes it is an expression of an illness that requires treatment.
The seventh reason is a chronic or inflammatory disease that has not yet been diagnosed. Diabetes, kidney diseases, liver diseases, heart diseases, lung diseases, autoimmune diseases, prolonged infections, inflammatory bowel diseases, and sometimes malignancy can manifest as fatigue. Usually, though not always, additional signs will appear: Unexplained weight loss, prolonged fever, night sweats, new pain, prolonged diarrhea, blood in the stool, shortness of breath, leg swelling, a prolonged cough, or a sharp decline in functioning. These are not signs that should be explained away by a heavy workload.
There is also a more complex condition, chronic fatigue syndrome, or by its medical name myalgic encephalomyelitis. This refers to severe fatigue that lasts for at least 6 months, does not improve with rest, impairs functioning, and is sometimes accompanied by worsening after exertion, muscle and joint pain, headaches, unrefreshing sleep, brain fog, and a flu-like feeling. This is a real and limiting condition, but it is important not to jump to it before more common and treatable causes have been ruled out.
When should you consult a doctor?
If the fatigue lasts for more than two weeks despite rest, hydration, a reasonable diet, and reducing workload; if it worsens; if it impairs functioning; or if it is accompanied by weight loss, fever, night sweats, shortness of breath, chest pain, heart palpitations, blood in the stool, new weakness, confusion, or a significantly low mood. The British National Health Service notes that common causes of fatigue include lack of sleep, an unhealthy lifestyle, stress, depression, hormonal changes, and illnesses such as mononucleosis and coronavirus, but fatigue that is not relieved by rest and sleep may indicate a medical condition that requires consultation.
For the meeting with the doctor, it is best to arrive prepared: When the fatigue started, what has changed in life, what sleep looks like, if there is snoring, what medications are taken, if there is a change in weight, appetite, bowel movements, menstrual cycle, mood, or physical fitness. An initial investigation may include a complete blood count, chemistry, kidney and liver functions, glucose, thyroid functions, iron, ferritin, B12, and additional tests as needed. Not every person needs all the tests, but almost every person with persistent fatigue needs an organized medical conversation.
<br>The friend on your wrist: The simple tool that can help you monitor
Meanwhile, a simple aid that can assist in identifying sleep patterns is the smartwatch. New models of watches and health bands have become a sort of basic home sleep laboratory: They measure throughout the night the duration of sleep, the number of awakenings, heart rate, respiratory rate, and sometimes also blood oxygen saturation and an estimated division into sleep stages. In the morning, a report is generated that can show if sleep is too short, fragmented, accompanied by a high heart rate, or possible drops in respiratory metrics.
It is important to remember that watches do not replace a medical sleep test, and the evaluation of sleep and dream stages is not as accurate as in a sleep laboratory, but consistent tracking over several weeks can provide a useful picture for both the patient and the doctor. If the watch repeatedly points to fragmented sleep, multiple awakenings, drops in oxygen saturation, or an abnormal nocturnal heart rate, especially alongside daytime fatigue, snoring, or waking up with a choking sensation, it is advisable to bring the data to the family doctor and consider an organized sleep evaluation.
Dr. Itay Gal is a specialist in pediatrics, a sports and aviation physician, and the medical commentator for Maariv. For more articles click here