A student fell asleep at the wheel and killed a man after “partying heavily” the previous night.

Alisdair Grant caused a head-on smash with Gerry Lewis in East Ayrshire in March 2014.

The 21 year-old had recently served a ban for drink driving before the fatal crash.

Mr Lewis, a conservationist, never recovered with his loss having a “profound” effect on his grief-stricken wife.

Grant now faces a lengthy jail-term after he admitted causing death by dangerous driving.

The collision occurred on the A719 close to the Ayrshire village of Waterside.

Grant, of Kilmarnock, was not long back on the road having been banned for a year in December 2012 for drink driving.

Prosecutor Mark McGuire told the court: “Text messages recovered from his mobile phone sent that day indicate he had been partying heavily the night before.

“Around two hours before the collision – in response to someone asking if he was fit to drive – he replied he thought he would be soon. The texts made it clear Grant was tired.”

Mr Lewis was meantime driving his Suzuki 4x4 in the opposite direction. The 54 year-old was going with his wife Sarah to see his mother in Glasgow.

The hearing was told as the two vehicles approached, Grant’s Fiat drifted “without warning” into the path of Mr Lewis’s car.

The advocate depute went on: “From what Mrs Lewis could see, there was no attempt to brake by Grant. He had fallen asleep.”

Mr Lewis, who had worked for North Lanarkshire Council for 20 years, died from chest and abdominal injuries.

Judge Lord Boyd deferred sentencing for reports.