Causes of Constant Tiredness and Fatigue

Do you wake up already tired, and by the afternoon your energy is completely gone? The causes of constant tiredness vary widely: from lack of sleep and stress to iron deficiency, an underactive thyroid or diabetes. Fatigue is not a disease in itself but a signal from the body. In this article we look at the most common causes, which tests are worth discussing with a doctor and which daily habits genuinely help.

Normal tiredness and chronic fatigue: what is the difference?

Feeling tired after a hard working day, a sleepless night or a long trip is natural. This kind of tiredness usually passes after good rest and one or two nights of proper sleep.

It is a different matter if weakness lasts for weeks, does not go away with rest and gets in the way of daily life. The NHS (the UK National Health Service) advises seeing a doctor if you have felt tired for a few weeks and do not know why. Behind this kind of constant tiredness and sleepiness there is often a cause that can be found and treated.

What are the causes of getting tired quickly?

The causes can be roughly divided into three groups. The first is lifestyle: too little or poor-quality sleep, an unhealthy diet, little movement, a lot of caffeine in the evening. The second is mental state: stress, low mood, hard periods such as bereavement or caring for a new baby. The third is physical illness and conditions, including hormonal changes (pregnancy, menopause), recent infections and the effects of some medicines.

The table below summarises the main causes worth discussing with a doctor. It is not for self-diagnosis but to help you prepare for the appointment:

Possible cause	Additional signs	Test a doctor may order
Iron deficiency anaemia	Pale skin, shortness of breath, palpitations, headaches	Full blood count, ferritin
Vitamin B12 or folate deficiency	Pins and needles in hands and feet, sore red tongue, memory problems	Blood B12 and folate levels
Vitamin D deficiency	Bone and muscle pain, muscle weakness	25(OH)D test
Underactive thyroid (hypothyroidism)	Feeling cold, weight gain, constipation, dry skin	TSH and T4
Diabetes	Strong thirst, frequent urination, unexplained weight loss	Blood glucose, glycated haemoglobin (HbA1c)
Pauses in breathing during sleep (sleep apnoea)	Loud snoring, gasping or choking in sleep, daytime sleepiness	Doctor's assessment, a sleep study if needed
Depression, chronic stress	Low mood, loss of interest, disturbed sleep	Consultation with a psychotherapist or psychiatrist

Iron deficiency: a common cause of tiredness in women

According to the NHS, iron deficiency anaemia is the most common type of anaemia. Iron is needed to make haemoglobin, and haemoglobin carries oxygen from the lungs to the whole body. When iron is short, tissues receive less oxygen and a person tires quickly.

Among the causes of tiredness in women, iron deficiency has a special place. Its causes include:

heavy and long periods;
pregnancy (especially when the diet is low in iron);
hidden blood loss from the stomach or bowel, for example with an ulcer or long-term use of painkillers such as ibuprofen and aspirin.

Signs: weakness, shortness of breath, noticeable heartbeats, pale skin, headaches. Less often there may be ringing in the ears, hair loss, spoon-shaped nails or cravings for unusual things such as chalk or clay. For more detail, see the iron deficiency anaemia page, and for how to read your results, our article on anaemia grades and the haemoglobin test.

Can low vitamin D and B12 cause fatigue too?

Yes, they can. For vitamin B12 or folate deficiency the NHS lists extreme tiredness and lack of energy, pins and needles, a sore red tongue, mouth ulcers, muscle weakness, vision problems and changes in mood and memory. This deficiency can occur with or without anaemia.

Who is at risk? Older people, those who do not eat sources of B12 (meat, fish, eggs, dairy) and people taking certain medicines long term, such as stomach acid reducers or anticonvulsants. The NHS stresses that early diagnosis matters because some complications can be permanent.

Vitamin D deficiency may cause muscle weakness, bone pain and weakness, but these signs are not specific. More on this: vitamin D deficiency symptoms.

Thyroid and diabetes: causes that are often overlooked

With an underactive thyroid (hypothyroidism) symptoms usually develop slowly and unnoticed. The NHS lists extreme tiredness, feeling colder than usual, weight gain, constipation, trouble concentrating, low mood, dry skin and hair loss, a hoarse voice and irregular periods. It is diagnosed with blood tests for TSH and T4. An overactive thyroid can also come with tiredness.

Diabetes is also on the NHS list of causes of tiredness. If constant thirst, frequent urination, unexplained weight loss and weakness come together, your blood sugar needs checking. It is a simple test, yet many people skip it for years.

Sleep, stress and mood: the "invisible" causes of fatigue

Sometimes tests come back normal, yet the person still feels drained. Then it is worth looking at sleep quality and mental state. Insomnia, phone use at night and shift work disrupt sleep. With sleep apnoea a person can spend 8 hours in bed but not sleep deeply because breathing keeps pausing. If your family says you gasp or choke in your sleep, be sure to tell your doctor.

Chronic stress and depression also come with marked fatigue. Struggling to get up in the morning, losing interest in everything and long-lasting low mood are not "laziness". You can read more on the chronic stress page. Seeing a mental health professional is nothing to be ashamed of; it is taking care of your health.

After flu, COVID-19 and other infections, weakness may last for several weeks. Some medicines also cause tiredness, so tell your doctor everything you take.

Daily habits that reduce fatigue

If the cause lies in lifestyle, simple habits make a big difference. Based on NHS advice:

Sleep schedule. Go to bed and get up at the same time every day; aim for 6–9 hours of sleep.
The hours before bed. Avoid heavy meals, tea and coffee, energy drinks and exercise in the couple of hours before bed. A late, fatty plov for dinner can also make sleep heavier.
Screens. Put away your phone and switch off the TV an hour before bed.
Bedroom. Keep it dark, quiet and cool.
Diet. A balanced diet of vegetables, fruit, pulses, meat or fish; do not skip breakfast.
Movement. Regular physical activity, even a daily walk, supports energy. Stopping activity because of tiredness often makes it worse.
Smoking and alcohol. Stop smoking and limit alcohol.
Rest. Take short breaks during the day and build relaxing habits before bed, such as reading or quiet music.

Important: if weakness persists after several weeks of these habits, the cause should be looked for with tests. Taking vitamins or "energy" products at random may mask the cause.

When to see a doctor

Following NHS advice, see a doctor if:

you have felt tired for a few weeks without a clear reason;
fatigue interferes with your work, family or daily life;
tiredness comes with unexplained weight loss or mood changes;
you have been told you gasp, choke or stop breathing in your sleep.

The following signs are an emergency: call an ambulance (103 in Uzbekistan) or go to an emergency department:

chest pain, severe shortness of breath or fainting;
black, tarry stools, or blood in vomit or stool;
sudden severe weakness, slurred speech or a drooping face;
thoughts of harming yourself.

Before the appointment, keep a note for a week or two of your sleep hours, meals, periods (for women) and when the tiredness gets worse. This helps the doctor find the cause faster.

How Nutva Immuno can help

Let us be clear first: no supplement on its own resolves the cause of fatigue, and none replaces tests and a doctor's examination. If your diet is low in vitamins and minerals and your doctor has no objection, a vitamin and mineral complex can complement your nutrition.

Nutva Immuno is a dietary supplement that supports normal immune function. One capsule (500 mg, 60 capsules per pack) contains: iron glycinate 68 mg, zinc picolinate 125 mg, manganese bisglycinate 3 mg, copper bisglycinate 4 mg, iodine 150 mcg, selenium 60 mcg, molybdenum bisglycinate 60 mcg, chromium picolinate 100 mcg, vitamin C 200 mg, vitamin A 2 mg, vitamin E 20 mg, vitamin D3 1000 IU, B3 18 mg, B5 10 mg, B6 (pyridoxal-5-phosphate) 4 mg, B1 3 mg, B2 4 mg, B9 (methylfolate) 400 mcg and B12 (methylcobalamin) 40 mcg.

The product is not a medicine. It does not replace a balanced diet, enough sleep, physical activity or medicines prescribed by a doctor. Permit number: №1578927 (Ministry of Health of Uzbekistan), manufacturer NUTVA PHARM LLC.

Precautions. The product contains iron: with diagnosed anaemia the iron dose is set by a doctor. Check with a doctor before combining it with other iron or vitamin supplements. During pregnancy and breastfeeding, take it only after agreeing with your doctor. Directions for use: follow the leaflet on the pack and your doctor's advice.

Frequently asked questions

Why am I always tired and sleepy?

The most common causes are not enough or poor-quality sleep, stress, little movement and an unhealthy diet. But iron deficiency, an underactive thyroid, diabetes and sleep apnoea can feel the same. If it lasts a few weeks, see a doctor.

Which vitamin deficiency causes tiredness?

Iron, vitamin B12, folate and vitamin D deficiency are the ones most often discussed. But only a blood test shows which one is actually low, because the signs are very similar.

What tests should I have for constant fatigue?

Your doctor puts the list together based on your complaints and examination. It usually includes a full blood count, ferritin, blood glucose and thyroid hormones, and sometimes B12, folate and vitamin D.

What causes tiredness in women?

Women more often have iron deficiency because of heavy periods and pregnancy. Hormonal changes (pregnancy, menopause), thyroid problems and the stress of juggling work and home are also important factors.

Can I take vitamins for tiredness?

Taking vitamins without knowing the cause is not recommended. For example, iron taken without a test can hide the cause of anaemia, including hidden bleeding. Get checked first, then decide with your doctor whether you need a supplement.