Why am I so tired all the time?

Fatigue is the symptom people apologise for raising. It has no number attached to it, it sounds like a complaint about modern life, and many people have already been told it is stress. It is also one of the most productive symptoms to investigate properly, because a small number of common, testable conditions account for a large share of it.

The first useful question is not what causes tiredness, but which kind you have. Sleepiness — falling asleep in a chair, in a meeting, at a traffic light — points toward sleep quality and sleep apnoea. Muscle fatigue — arms heavy on the stairs, legs giving up early — points toward anaemia, thyroid disease and deficiency states. Mental exhaustion without physical weakness points toward mood, sleep and chronic stress. Most people have a mixture, but the dominant flavour directs the search.

Iron deficiency. This is the commonest treatable cause in India, and it is widespread among women of reproductive age, in adolescents and in anyone on a predominantly plant-based diet. Iron from vegetarian sources is absorbed less efficiently, and tea or coffee taken with meals reduces that absorption further. Heavy periods are a frequent and under-discussed contributor. Crucially, fatigue begins when stores fall, well before haemoglobin drops — so a normal haemoglobin with a low ferritin is a real finding, not a technicality.

Vitamin B12 deficiency. Common in vegetarian diets, since B12 comes almost entirely from animal sources, and also caused by poor absorption — including in people on long-term metformin or acid-suppressing medication. It produces fatigue alongside tingling in the hands and feet, poor concentration, a sore tongue and, when advanced, unsteadiness.

Thyroid disease. Hypothyroidism is common, particularly in Indian women, and produces fatigue with cold intolerance, dry skin, hair fall, constipation, weight gain and low mood. It is one test away.

Vitamin D deficiency. Widespread across India, including in people who work outdoors, and associated with fatigue, muscle aches and low mood. Worth correcting; rarely the entire explanation.

Sleep, and what interrupts it. Obstructive sleep apnoea is substantially under-diagnosed here. Loud snoring, witnessed pauses in breathing, unrefreshing sleep and daytime sleepiness are the pattern, and it is worth pursuing because treating it changes energy, blood pressure and glucose together.

Metabolic and mood causes. Undiagnosed or poorly controlled diabetes produces fatigue, often with thirst and night-time urination. Depression and sustained anxiety produce genuine physical exhaustion, and they frequently sit alongside the physical causes rather than instead of them.

Everything else. Medicines — some blood-pressure agents, antihistamines, antidepressants — are a common and forgettable contributor. Kidney and liver disease, heart failure, chronic infection including tuberculosis, coeliac disease, and fatigue persisting after a viral illness all belong on the list. These are less common, which is why the story and examination matter as much as the tests.

ⓘThis information is educational and not a diagnosis.

Most fatigue is not dangerous. A specific set of accompaniments changes that, and they are worth knowing.

Seek prompt assessment if fatigue comes with chest pain or breathlessness on mild exertion such as one flight of stairs; with weight loss you did not intend; with fever, drenching night sweats or a lump you can feel; with blood in the stool or black tarry stools; or with yellowing of the eyes or skin. Very heavy periods alongside exhaustion are a common and correctable combination that goes unmentioned for years.

New numbness, tingling, unsteadiness on your feet or weakness on one side needs urgent attention rather than a routine appointment. So does fatigue with excessive thirst and frequent night-time urination.

If you are having thoughts of harming yourself, or feel you cannot go on, please seek help today — from a doctor, a mental health professional, or someone you trust. That is a medical situation and it responds to treatment.

Outside these, it is reasonable to be seen when tiredness has persisted beyond four to six weeks despite adequate sleep, or when it is changing what you can do at work or at home.

Spend two weeks building a picture rather than guessing at one. Record when you go to bed and when you wake, how many times you wake in the night, energy at three points in the day, and whether anyone has heard you snore or stop breathing. Note your periods if you have them, and every medicine and supplement you take with the date you started it.

Then get a first round of tests rather than treating blindly. A reasonable starting panel is a complete blood count with ferritin, thyroid function, vitamin B12, vitamin D, HbA1c, and kidney and liver function. These are inexpensive and available at most Indian laboratories, and together they explain a large share of unexplained fatigue. Ordering them alongside a consultation means the results are read against your history rather than against a reference range alone.

Avoid starting iron or B12 supplements before testing. Supplementation changes the results and can leave the actual cause — heavy periods, poor absorption, blood loss from the gut — unexamined for months. If a deficiency is found, the more useful question is why it happened.

While you wait, protect the basics: a consistent sleep window, movement most days even briefly, and a proper protein source at each meal. If tests are normal and fatigue persists, that is a reason for a fuller assessment, including sleep and mood, rather than a reason to accept it.