Lethargy

The symptoms of feeling lethargic will depend on what it is causing it. Common lethargy symptoms to look out for include:

• Feeling exhausted
• Lack of energy
• Headache
• Dizziness
• Muscle weakness
• Impaired decision making or judgement
• Slow reflexes
• Anxiety
• Irritability
• Being less alert

If your baby or child is difficult to rouse, you should seek medical attention immediately.

Feeling lethargic can be a symptom of:

Chronic Fatigue Syndrome

Chronic Fatigue Syndrome (CFS) is a term used to describe extreme tiredness – it’s also known as ME (myalgic encephalomyelitis). CFS is not well understood, but certain things are thought to contribute to is, such as mental health conditions, a viral infection, a hormonal imbalance or because of a combination of other factors.

Depression

Depression is a mental health disorder and can affect you in a number of different ways, one of which is feeling like you have a lack of energy. Read more about depression.

Anxiety

Experiencing anxiety every so often is sometimes completely normal, but if you feel constantly anxious, this can cause symptoms including lethargy. Read more about it anxiety.

Coeliac disease

Coeliac disease affects one in 100 people across the UK, according to Coeliac UK, although not everyone realises that they have the condition. It’s a type of food intolerance that causes damage to the gut when gluten is eaten.

Coeliac disease is accompanied by other symptoms as well as lethargy, such as anaemia, weight loss and diarrhoea. A gluten free diet is usually advised if you’re diagnosed with his condition.

Iron deficiency - anaemia

Anaemia is another reason for feeling lethargic, sluggish and run down. Women who have heavy periods or who are pregnant are particularly prone to anaemia, but men can also feel tired due to iron deficiency.

Fever

If you have a fever, one of the symptoms can be feeling extremely lethargic. Once the underlying cause of the fever is treated or resolves on its own, you should start feeling yourself again soon after.

Sleep apnoea

Sleep apnoea happens when your throat becomes floppy during sleep, which results in reduced blood oxygen levels and interrupted breathing, which will wake you up at night. With sleep interrupted throughout the night, it is common for you to feel lethargic the next day.

Diabetes

Diabetes, type one or two, is a long-term condition, and managing it daily can make you feel lethargic. Undiagnosed diabetes has other tell-tale symptoms as well as lethargy, such as weight loss, thirst and frequent urination.

Underactive thyroid

Feeling lethargic can be a result of an underactive thyroid gland. The condition is more common in women and can result in lethargy, aching muscles and weight gain.

Carbon monoxide poisoning

Inhaling too much carbon monoxide can be life threatening and it can make you very drowsy. If you think you may be at risk, seek help urgently.

Glandular fever

Glandular fever is a viral infection and causes lethargy, along with a sore throat, fever and swollen glands. It typically clears up in six weeks. However, glandular fever can leave you feeling tired for several months afterwards.

Seasonal Affective Disorder

Seasonal affective disorder (SAD) is a depressive disorder that has a seasonal pattern, typically experienced in the winter. If you feel particularly lethargic during the winter months, this could be a potential cause.

Restless legs

Restless legs can keep you awake at night and lead to feeling lethargic the next day. It is when you have uncomfortable leg sensations, such as an urge to keep moving your legs, or spontaneous leg jerking.

Heart disease

The first signs of heart disease can be lethargy or exhaustion caused from completing everyday tasks, such as climbing stairs.

Dehydration

Dehydration can cause you to feel lethargic. Drinking sips of water helps the body to flush out toxins and rehydrate you, but dehydration can be deadly, especially in children. Find out more dehydration.

Lyme disease

This is an infectious disease transmitted to humans by ticks. As well as developing a rash, you’ll start to feel unwell and tiredness is one of the main symptoms. Speak to a doctor urgently if you think you may be at risk.

PMS

PMS (premenstrual syndrome) can affect how women feel in the days running up to their period, which can include making you feel tired.

This is only a small selection of the conditions that can cause lethargy. If it is impacting your daily life, you should see a GP – they can then investigate it further for you and help you find the cause.