Parkinson's disease is a condition that causes the brain to become progressively more damaged over time, said the NHS. You could be at risk of the neurodegenerative condition if your voice changes over time, it's been revealed.
Parkinson's is caused by a loss of nerve cells in a specific part of the brain.
These nerve cells are used to help send messages between the brain and the nervous system.
Parkinson's disease symptoms tend to develop gradually, and only appear as mild at first.
One of the more under-recognised problems of Parkinson's is extreme tiredness, it's been claimed.
Fatigue is commonly reported in Parkinson's disease patients.
It's considered to be the most annoying sign of the neurodegenerative condition in around a third of all patients.
It's one of the earliest symptoms of Parkinson's, and tends to stay throughout the duration of the condition.
But, scientists still aren't 100 percent clear on why fatigue is a symptom of Parkinson's disease.
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"Fatigue is a common but under-recognised problem for people with Parkinson's disease," said the American Parkinson Disease Association.
"Fatigue can be defined as an unpleasant sensation of lacking energy, making the performance of routine activities, physical or mental, a strain.
"About one-third of people with PD consider fatigue their single most bothersome symptom, even more than the motor symptoms of PD such as tremor, slowness, stiffness and difficulty with walking and balance.
"Fatigue in [Parkinson's] tends to develop early in the disease, usually in the first few years, if it is going to develop at all."
But, just because you're feeling more sleepy than normal, it doesn't necessarily mean that you're at risk of Parkinson's.
Feeling fatigued is very common, and may be caused by not getting enough sleep, spending long hours at work, or by excessive stress.
Doing too much exercise or drinking too much alcohol could also lead to extreme tiredness.
Your fatigue is more likely to be caused by Parkinson's if it's accompanied by more common warning signs of the neurodegenerative condition.
Common signs of Parkinson's disease include tremors, slow movement, and muscle stiffness.
The muscle stiffness makes facial expressions more difficult, said the charity.
Tremors usually start in the hand or the arm, and are more likely to occur when the arm is relaxed.
There are about 127,000 people in the UK with Parkinson's disease - the equivalent to about one in 500 people.