Stephan Allen Tunbridge didn't wake to a blaring alarm clock or the twittering of birds on December 13.

He woke when the car he was driving crashed through a fence.

Tunbridge was driving near Waitotara when he fell asleep at the wheel, police prosecutor Sergeant Stephen Butler told the Whanganui District Court on Tuesday. The car drifted off the road at a moderate right-hand bend, went through a farm fence, and coasted "almost 50 metres through a swamp" before coming to a stop. Tunbridge, who has pleaded guilty to careless driving, suffered scratches to his hands from a broken window. He told police he felt himself "dozing off" and woke up when his car crashed through the fence.

Judge David Cameron fined Tunbridge $300 and $130 court costs.