Phil Benbow, secretary of the Llanberis Mountain Rescue Team, said conditions on many mountains were treacherous.

BBC: North West Wales

"We deployed two members of the team to help the man who was fully equipped with crampons and ice axe, " said Mr Benbow.

BBC: North West Wales

Dr Alistair Benbow, medical director of SmithKline Beecham, said that ropinirole was associated with sleepiness, but only in a tiny minority of patients, and that the company had never previously come across patients who experienced sudden sleep attacks.

BBC: Parkinson's patients face sleep danger