Suffering nightmares in your sixties could be an early warning sign of Parkinson's, a study claims. 

Researchers found men who endured bad dreams at least once per week were up to three times more likely to develop the crippling condition.

The findings, from academics at the University of Birmingham, come from a 12-year analysis of 3,800 older men.

Dr Abidemi Otaiku and colleagues have now urged people who experience changes in their dreams in older age to 'seek medical advice'.

Identifying Parkinson's — which causes muscle shaking and stiffness — early is key to monitoring its progress and treating it.

It gradually gets worse over time as more brain cells die, with patients eventually left struggling to complete day-to-day tasks.

No conclusive Parkinson's tests exist yet, meaning patients often are not diagnosed until tell-tale tremors set in.

Finding a way of spotting the condition earlier would be 'really beneficial', Dr Otaiku said.

Intense, vivid and frightening dreams may be one of the earliest signs of Parkinson's, the researchers now believe.

Parkinson's MAY trigger nightmares because of the damage it does to parts of the brain that regulate emotions during sleep, they said.

The study, published in the journal eClinicalMedicine, tracked 3,818 men between December 2003 to May 2016 who did not have Parkinson's at the start. All of the participants were aged 67 or above.

The men came from six centres across the US: Birmingham in Alabama, Minneapolis, Palo Alto and San Diego in California, Pittsburgh and Portland in Oregon.

Patients were asked to fill in a sleep questionnaire over four visits, which asked how often they had trouble sleeping because of bad dreams.

No definition was given for bad dream and participants could answer from zero to three times a week. 

Researchers also monitored Parkinson's diagnosis rates over the 12-year period to establish whether the condition was associated with sleep quality. 

They controlled for factors associated with both nightmares and Parkinson's, such as insomnia, depression, alcohol, smoking, diabetes and hypertension.

Results showed 91 men went on to develop Parkinson's over the study. 

Analysis found men who had difficulty sleeping because of bad dreams at least once a week were 2.01 times more likely to be diagnosed.

This rose to 3.38 times during the first five years of the study.

Early research into how parts of the brain causes dreaming suggests damage to the right frontal lobe can cause more distressing episodes.

This is something which occurs in Parkinson's patients because of the degenerative effects of the condition. 

Parkinson's affects around one in 500 Britons and one in 330 in the US, with most patients being in their 50s and over.

Boxer Muhammad Ali, comedian Billy Connolly and actor Michael J Fox count among those who live or have lived with the condition.