10 medical reasons for feeling tired

Any serious illness, especially painful ones, can make you tired. But some quite minor illnesses can also leave you feeling washed out. Here are 10 health conditions that are known to cause fatigue.

Sick or tired?

If you’re getting your eight hours of sleep a night but still feel exhausted, it’s time to see a doctor.

It’s also worth seeking medical advice if you have any of these symptoms:

  • confusion
  • dizziness
  • blurred vision
  • unexplained weight loss or gain
  • swelling
  • constipation
  • insomnia
  • depression 
  • headaches

1. Coeliac disease

This is a type of food intolerance, where your body reacts badly when you eat gluten a substance found in bread, cakes and cereals. One in 100 people in the UK are affected, but research suggests that up to 90% of them don’t know they have the condition, according to patient group Coeliac UK. Other symptoms of coeliac disease, apart from tiredness, are diarrhoea, anaemia and weight loss. Your GP can check if you have coeliac disease through a blood test.

Read more about coeliac disease.

2. Anaemia

One of the most common medical reasons for feeling constantly run down is iron deficiency anaemia. It affects around one in 20 men and post-menopausal women, but may be even more common in women who are still having periods.

Typically, you’ll feel you can’t be bothered to do anything, your muscles will feel heavy and you’ll get tired very quickly. Women with heavy periods and pregnant women are especially prone to anaemia.

Read more about iron deficiency anaemia.

3. Chronic fatigue syndrome

Chronic fatigue syndrome (also called myalgic encephalomyelitis or ME) is a severe and disabling tiredness that goes on for at least six months. There are usually other symptoms, such as a sore throat, muscle or joint pain and headache.

Read more about chronic fatigue syndrome.

4. Sleep apnoea

Sleep apnoea is a condition where your throat narrows or closes during sleep and repeatedly interrupts your breathing. This results in bad snoring and a drop in your blood's oxygen levels. The difficulty in breathing means that you wake up often in the night, and feel exhausted the next day.

It’s most common in overweight, middle-aged men. Drinking alcohol and smoking makes it worse.

Read more about sleep apnoea.

5. Underactive thyroid

An underactive thyroid gland means that you have too little thyroid hormone (thyroxine) in your body. This makes you feel tired. You’re also likely to put on weight and have aching muscles. It’s most common in women, and it happens more often as you get older.

Your GP can diagnose an underactive thyroid by taking a blood test.

Read more about having an underactive thyroid.

6. Diabetes

One of the main symptoms of diabetes, a long-term condition caused by too much sugar in the blood, is feeling very tired. The other key symptoms are feeling very thirsty, going to the toilet a lot and weight loss. Your GP can diagnose diabetes with a blood test.

Read more about diabetes and find out how to make smart sugar swaps.

Find your local diabetes support services.

7. Glandular fever

Glandular fever is a common viral infection that causes fatigue, along with fever, sore throat and swollen glands. Most cases happen in teenagers and young adults. Symptoms usually clear up within four to six weeks, but the fatigue can linger for several more months.

Read more about glandular fever.

8. Depression

As well as making you feel very sad, depression can also make you feel drained of energy. It can stop you falling asleep or cause you to wake up early in the morning, which makes you feel more tired during the day.

Read more about depression.

Find your local depression support services and your local depression self-help groups.

9. Restless legs

This is when you get uncomfortable sensations in your legs, which keep you awake at night. You might have an overwhelming urge to keep moving your legs, a deep ache in your legs, or your legs might jerk spontaneously through the night. Whatever your symptoms, your sleep will be disrupted and of poor quality, so you’ll feel very tired throughout the day.

Read more about restless legs.

10. Anxiety

Feeling anxious is sometimes perfectly normal. However, some people have constant, uncontrollable feelings of anxiety, which are so strong they affect their daily life. Doctors call this generalised anxiety disorder (GAD). It affects around around one in 20 people in the UK. As well as feeling worried and irritable, people with GAD often feel tired.

Read more about anxiety.

Find your local anxiety support services.

Glandular fever

An expert explains how glandular fever is caused, how it's passed on and how to recognise the symptoms.

Media last reviewed: 29/05/2015

Next review due: 29/05/2017

Page last reviewed: 21/02/2015

Next review due: 21/02/2017

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