Feeling tired all the time is one of the most common health complaints in the UK. The NHS lists it among the top reasons people visit their GP, and most of us have asked the question at some point: why am I always tired, even when I think I am getting enough sleep? The causes range from straightforward lifestyle factors to medical conditions that need investigation. This guide covers the most common reasons, what you can do at home, what your pharmacist can suggest and when it is time to see your doctor.
Key takeaways
- Persistent tiredness usually has more than one cause: poor sleep quality, stress, inactivity, diet and dehydration are among the most common lifestyle factors.
- Several medical conditions can cause ongoing fatigue, including iron deficiency anaemia, underactive or overactive thyroid, type 2 diabetes, sleep apnoea and depression.
- The NHS advises seeing your GP if you have been tired for several weeks without a clear reason, or if fatigue is affecting your daily life.
Common causes of persistent tiredness
The NHS groups the causes of tiredness into three broad categories: lifestyle, psychological and medical. In practice, several of these often overlap. Someone who is stressed at work may sleep badly, eat irregularly and cut back on exercise, all of which feed into the same cycle of fatigue.
Lifestyle causes
Poor sleep quality is the most obvious starting point. According to the University of Michigan, many people who believe they are sleeping enough are actually experiencing non-restorative sleep: frequent micro-arousals, snoring, an irregular schedule or too much screen time before bed can all reduce the amount of deep, restorative sleep you get without you realising it.
Inactivity is a less intuitive cause. It may seem logical that resting more would reduce tiredness, but the opposite is often true. Regular physical activity improves sleep quality, boosts circulation and helps regulate energy levels. The NHS lists a sedentary lifestyle as one of the most common contributors to persistent fatigue.
Other lifestyle factors include drinking too much caffeine (which can disrupt sleep even when consumed earlier in the day), drinking too much alcohol (which fragments sleep), dehydration and eating irregularly or relying on high-sugar foods that cause energy crashes.
Psychological causes
Stress, anxiety and low mood are among the most common reasons for feeling tired all the time. The NHS notes that emotional exhaustion can be just as draining as physical exertion, and that ongoing worry, life changes or relationship difficulties often show up as persistent tiredness before a person recognises the psychological cause. Healthline adds that chronic stress raises cortisol levels, which can interfere with sleep quality and leave you feeling drained even after a full night in bed.
Depression frequently involves fatigue as a core symptom, not a side effect. If you feel persistently low, have lost interest in things you used to enjoy and are tired regardless of how much you sleep, it is worth speaking to your GP.
Medical causes
When tiredness persists despite addressing lifestyle and stress, a medical cause may be involved. The conditions the NHS highlights include:
- Iron deficiency anaemia. One of the most common medical causes of fatigue, particularly in women with heavy periods, pregnant women and people on plant-based diets. A simple blood test can confirm it.
- Underactive thyroid (hypothyroidism). The thyroid gland produces hormones that regulate metabolism and energy. When it is underactive, tiredness, weight gain and feeling cold are typical symptoms.
- Type 2 diabetes. Persistently high blood sugar can cause fatigue, thirst, frequent urination and blurred vision.
- Sleep apnoea. A condition in which the throat narrows or closes during sleep, causing repeated waking. The Penn State Health team notes that many people with sleep apnoea do not realise they are waking repeatedly and simply feel exhausted during the day.
- ME/CFS (myalgic encephalomyelitis / chronic fatigue syndrome). A long-term condition causing severe fatigue that does not improve with rest. The University of Michigan notes that long COVID can also cause similar prolonged fatigue.
Other possible medical causes include vitamin D or vitamin B12 deficiency, coeliac disease, heart failure and certain medications (including antihistamines, blood pressure drugs and some antidepressants). Your GP can investigate these with blood tests and further assessment.
What you can do at home
The NHS self-help guide for fatigue recommends a series of practical steps that address the most common lifestyle causes. None of these is a quick fix, but taken together they can make a meaningful difference over several weeks.
- Eat regularly and do not skip meals. Aim for three meals a day with healthy snacks if needed. Avoid long gaps between eating, which can cause blood sugar dips and energy crashes.
- Get moving. Even a short daily walk can improve energy levels. The NHS notes that regular exercise is one of the most effective ways to reduce tiredness, even though it may feel counterintuitive when you are already tired.
- Improve your sleep routine. Go to bed and wake up at the same time each day, keep your bedroom cool and dark, avoid screens for at least an hour before bed and cut caffeine from the afternoon onwards.
- Drink more water. Mild dehydration is a common and easily overlooked cause of fatigue. Aim for six to eight glasses of fluid a day, mostly water or sugar-free drinks.
- Cut back on alcohol. Alcohol may help you fall asleep, but it reduces the quality of your sleep and can leave you feeling more tired the next day.
- Manage stress. The NHS suggests talking therapies (available free on the NHS through self-referral), regular breaks during the working day and relaxation techniques such as yoga or mindfulness.
It sounds contradictory, but one of the best ways to fight tiredness is to move more. The NHS recommends at least 150 minutes of moderate activity per week. Even starting with a 10-minute walk each day can help. Regular movement improves sleep quality, circulation and mood, all of which contribute to feeling more alert during the day.
What your pharmacist can suggest
If you have been feeling tired and suspect a straightforward cause, your pharmacist can be a useful first port of call. They can advise on several things without the need for a GP appointment:
- Iron supplements. If your diet is low in iron or you have heavy periods, your pharmacist can suggest an over-the-counter iron supplement and advise on the best form and timing. However, it is generally better to get a blood test first to confirm whether iron deficiency is the actual cause.
- Vitamin D supplements. Public Health England recommends that everyone in the UK consider taking a 10 microgram (400 IU) daily vitamin D supplement during autumn and winter. Low vitamin D is a common and often unrecognised contributor to tiredness.
- Vitamin B12. If you follow a vegan or largely plant-based diet, your pharmacist can advise on B12 supplementation, since this vitamin is found almost exclusively in animal-based foods.
- Sleep aids. Short-term options such as antihistamine-based sleep aids (diphenhydramine or promethazine) are available without prescription. Your pharmacist can explain how they work and when they are appropriate. These are not recommended for long-term use.
A pharmacist can also help you decide whether your tiredness warrants a GP visit rather than self-treatment.
Natural and traditional remedies
Several natural and traditional remedies are marketed for tiredness and fatigue. The evidence behind them varies considerably.
B vitamins and iron from food. The strongest evidence for addressing fatigue naturally comes from ensuring your diet provides adequate iron, vitamin B12, folate and vitamin D. Iron-rich foods include red meat, lentils, chickpeas, dark leafy greens and fortified cereals. Vitamin C taken alongside plant-based iron sources improves absorption. These are well-established nutritional principles, not alternative medicine.
Magnesium. Some people use magnesium supplements for tiredness, and low magnesium levels can contribute to fatigue and poor sleep. The NHS does not list magnesium supplementation as a standard recommendation for tiredness, and most people who eat a balanced diet get enough. However, if your diet is restricted, a pharmacist or GP can advise.
Herbal remedies. Products containing ginseng, rhodiola rosea and ashwagandha are widely sold for energy and fatigue. Some small studies have reported modest benefits for perceived fatigue, but the evidence base is limited. A 2012 Cochrane review on ginseng for fatigue in cancer patients found insufficient evidence to draw firm conclusions, and no large, well-designed trials have established any herbal remedy as an effective treatment for general tiredness. These products are not regulated as medicines in the UK, and quality can vary between brands.
Tissue salts and homeopathic remedies. Kali phos 6x is traditionally associated with mental fatigue and nervous exhaustion in the tissue salt tradition. However, there is no clinical evidence that it is effective. The NHS does not recommend homeopathy as a treatment for any health condition.
When to see your GP
You have been tired for several weeks and cannot explain why.
Your tiredness is affecting your ability to work, look after yourself or carry out daily activities.
You feel tired alongside other symptoms such as unexplained weight loss, blood in your stools, heavy periods, muscle aches or a lump.
You snore loudly, gasp or stop breathing during sleep (or a partner has noticed this).
You feel persistently low, anxious or hopeless alongside your tiredness.
If you have sudden, severe tiredness with chest pain, breathlessness or confusion, call 999.
The NHS advises seeing your GP if you have been tired for a few weeks without knowing why or if fatigue is affecting your daily life. Your GP may arrange blood tests to check for iron deficiency, thyroid function, blood sugar, vitamin D and B12 levels, and can assess you for sleep disorders, depression or other underlying conditions.
Do not try to self-diagnose a medical cause of tiredness. Many of the conditions listed above are straightforward to identify with the right tests, and early assessment means earlier treatment.
Common questions
How much sleep do I actually need?
Most adults need between seven and nine hours of sleep per night, according to NHS guidance. However, sleep quality matters as much as quantity. If you are sleeping for eight hours but waking frequently, feeling unrested or snoring heavily, the sleep you are getting may not be restorative.
Can dehydration make you tired?
Yes. Even mild dehydration can cause fatigue, difficulty concentrating and headaches. The NHS recommends six to eight glasses of fluid a day. Water, lower-fat milk and sugar-free drinks all count. Tea and coffee count too, but try to limit caffeine intake, especially in the afternoon and evening.
Should I take a vitamin supplement for tiredness?
It depends on the cause. If a blood test confirms a deficiency (iron, vitamin D, B12 or folate), supplementation can help. Taking supplements without knowing whether you are deficient is unlikely to improve your energy and can sometimes cause harm, particularly with iron. Ask your GP for a blood test before self-supplementing.
Why am I still tired after sleeping all night?
Non-restorative sleep is a common reason. Causes include sleep apnoea, stress, an inconsistent sleep schedule, alcohol, caffeine, screen use before bed and sleeping in a room that is too warm. If you regularly feel unrefreshed after a full night, speak to your GP, who can assess whether a sleep disorder may be involved.
When should I worry about tiredness?
If tiredness persists for several weeks without a clear explanation, is getting worse, or comes with other symptoms such as unexplained weight loss, breathlessness, heavy periods, persistent pain or changes in mood, see your GP. Most causes of persistent tiredness are treatable once identified.
Independent guides to natural remedies and supplements, checked against NHS and EFSA references.