6 medical reasons why you might be feeling tired all the time

How often do you ask yourself: “Why am I so tired all the time?”

We all know that burning the midnight oil, while juggling a busy schedule, is bound to leave us feeling sluggish, cranky and craving coffee the morning after – but if you’re getting enough sleep and still suffering from constant low energy, it’s worth considering whether there might be an underlying cause, possibly a health issue.

Around one in five people in the UK say they experience fatigue severe enough to impact their day-to-day routine and making it difficult to function.

Since the symptoms of ongoing tiredness may be a result of lots of a variety of medical conditions, it can be difficult – but important – to identify the cause of it.

With that in mind, we spoke to experts to find out the possible explanations for why you could be feeling drained, and the steps that you can take to feel re-energised.

1. Iron-deficiency anaemia

A lack of red blood cells can cause anaemia (Thinkstock/PA)

Iron-deficiency anaemia is a condition where a lack of iron in the body leads to a reduction in red blood cells, and around four million people in the UK are estimated to suffer from it. “People with anaemia can have a general lack of energy or tiredness, but also feel weak, faint or dizzy,” explains Dr Davina Deniszczyc, GP and medical director at Nuffield Health. “In severe cases, shortness of breath, pale complexion, brittle or dry nails and a sore and dry mouth and gums may develop.”

Women are more at risk of developing it, as around a third are thought to be low in iron due to heavy periods. A simple blood test can be done by your GP to detect anaemia, and iron supplements are typically prescribed, along with a diet of iron-rich foods (these include green, leafy vegetables, as well as meat and beans). “It’s really important to get an early diagnosis, as left untreated, anaemia can impact your immune system, making your more susceptible to illness or infection,” says Dr Deniszczyc.

2. Coeliac disease

Lethargy can also be a warning sign that something is wrong with your gut. It’s estimated around one in 100 people in the UK have coeliac disease (many of whom are yet to be diagnosed), a lifelong autoimmune disorder where consuming even the smallest amount of gluten triggers damaging – and potentially serious – reactions in the small intestines. Pain and digestive problems are also common symptoms. “If you have coeliac disease, your immune system reacts to wheat, barley or rye by attacking the lining of your intestine,” explains Dr Deniszczyc. If your GP thinks you may be coeliac, a blood test is usually the first step towards a confirmed diagnosis. There’s no cure but the condition can be managed with a strict gluten-free diet.

3. Dehydration

Take regular water breaks (Thinkstock/PA)

The solution for feeling more sprightly could be as simple as drinking more water. “Dehydration is no small matter; it can cause fatigue, lower back pain, bags under the eyes and anxiety, to name just a few symptoms,” says Emma Thornton, a nutritionist speaking on behalf of A.Vogel. “In fact, a group of scientists from the University of Connecticut’s Human Performance Laboratory found even mild dehydration, as a result of our ordinary daily activities, can alter a person’s mood, energy levels and memory function. As a good rule of thumb, aim to drink at least 1.5 litres of water a day.”

4. Chronic fatigue syndrome

This rare but debilitating condition, also known as CFS or ME, is believed to affect 0.4% of the population, and causes debilitating fatigue that comes on quickly and can severely impair your ability to function. “Chronic fatigue syndrome can cause severe tiredness that’s not relieved by rest or sleep,” says Dr Deniszczyc. “Other symptoms can include aching joints and muscles, loss of memory or concentration, gastric problems and disturbed sleep.” Since the symptoms are similar to many other conditions, it can be difficult to diagnose, but your GP might carry out a number of tests to rule out other conditions, such as lupus and multiple sclerosis, before making a diagnosis. CFS patients are usually offered graded exercise therapy (GET) as a treatment – a structured exercise programme that aims to gradually increase how long you can carry out a physical activity.

5. Depression

Depression can limit serotonin in the brain (Thinkstock/PA)

A knock to your mental health can take a severe toll on your quality of sleep and energy levels, and depression can deplete your brain of serotonin, which helps regulate your internal body clock. “Everyone can feel sad, tired or experience problems sleeping at times in our lives,” says Dr Deniszczyc. “Normally, these incidents of low mood will ease after a few days or weeks, but if your feelings begin to interfere with daily activities, it might be time to talk to your doctor as you could be experiencing depression.” Your GP can discuss treatment options with you too, such as therapy, counselling and/or anti-depressants, while regular exercise and a healthy diet can also help.

6. Poor diet

If your diet’s very poor, or you’re simply not eating enough, lack of nutrition could be making you tired – and too much sugar can have the same impact. “Making some simply dietary changes could make a big difference to energy levels,” says Thornton. “Thinking about the amount of sugary foods and fizzy drinks you are consuming, plus cutting down on stimulants such as caffeine will help. Watch out for erratic eating patterns too – eating heavy meals late at night may impact your sleep quality, which can result in food cravings and weight gain longer term.”

7. Underactive thyroid

Hypothyroidism – or an underactive thyroid – affects one in 70 women and one in 1,000 men, according to the NHS. “The thyroid gland produces hormones, which primarily regulate the body’s metabolism and digestive system, so if the thyroid gland is underactive, these hormones are not being produced as effectively,” explains Thornton. “This is why weight gain, as well as lethargy, are extremely common.” Key warning signs are tiredness, brain fog, thinning hair and feeling cold constantly. If concerned, discuss your symptoms with your GP, who can arrange a blood test. Treatment for underactive thyroid involves taking hormone replacement tablets to raise your thyroxine levels. While daily medication is usually required, with proper treatment, you should be able to lead a normal, healthy and fatigue-free life.

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