If you constantly feel exhausted regardless of how much sleep you get, remember these two letters: ME. According to the NHS, this stands for Myalgic Encephalomyelitis, also known as Chronic Fatigue Syndrome or ME/CFS. This long-term condition has no cure and can impact various parts of the body, but its most common symptom is severe fatigue.

Celebs like Cher even reportedly have this condition, according to previous reports from the Express. She reportedly became too exhausted to continue with her music or film career, stopping for almost two years to recover.

In a 2008 interview with USA today, Cher said: “I was sick for a long time. I went to Germany for some medicine and treatment.

“They have things overseas we never dreamed existed. When I was first diagnosed in the late 80s, I had doctors telling me I was crazy. I was sick constantly and almost died from pneumonia. You never lose it, and it really takes the life out of you.”

Sadly the condition can affect anyone, including children, and there are four main symptoms to look out for. So what are they? Here is what you need to know.

What are the symptoms of ME/CFS?

• feeling extremely tired all the time (fatigue), which can make daily activities like taking a shower, or going to work or school, difficult
• sleep problems, including insomnia, sleeping too much, feeling like you have not slept properly and feeling exhausted or stiff when you wake up
• problems with thinking, concentration and memory (brain fog)
• symptoms getting worse after physical or mental activity, and possibly taking weeks to get better (also called post-exertional malaise, or PEM)

Some people with ME/CFS may experience pain in different areas of the body or flu-like symptoms, such as a high temperature, headache, and aching joints or muscles. Because ME/CFS symptoms are similar to those of other conditions, it’s important to see a GP for a proper diagnosis. According to the NHS, this tye of exhaustion isn’t simply due to a lack of sleep as it persists even after getting plenty of rest, leaving individuals feeling drained and unwell.

The NHS explains: "The extreme tiredness (fatigue) associated with ME/CFS does not go away with rest or sleep. This can make it difficult to carry out everyday tasks and activities. Most people with ME/CFS describe their fatigue as overwhelming and a different type of tiredness from what they've experienced before."

You may also find that:

• you do not feel refreshed after sleeping – like you have not had a proper good night's rest
• you keep waking up during sleep
• you feel stiff, tired or have flu-like symptoms when waking up
• you feel very tired and sleepy during the day

If you have ME/CFS, it's also common to have problems remembering certain words, names or numbers. You may also find that you find it hard to concentrate or focus on more than one thing at a time. In addition to both of these, the health service warns that if you jave problems remembering things that happened recently or are slow to speak or react to things, you may have ME.

Other symptoms of ME/CFS can include:

• muscle or joint pain
• fast or irregular heartbeats (heart palpitations)
• feeling dizzy or sick
• headaches
• muscle twitches or spasms
• a sore throat or sore glands that are not swollen
• having hot flushes or cold chills if the temperature changes
• feeling dizzy, sick or fainting when standing up from a sitting or lying position
• being very sensitive to light, sound, touch, taste and smell
• flu-like symptoms
• intolerance to alcohol or certain foods or chemicals