Meanwhile, an ambulance was called and medics treated cuts to the victim's head and lip.
Confused and disoriented, he was later admitted to Wanganui Hospital and diagnosed with a bleed on his brain. The man was later transferred to Kenepuru Hospital and not discharged until May 7, 2012.
For a further six months, he was not allowed to drive and was unable to work full-time.
Judge David Cameron said Cowley's criminal history indicated he had an alcohol problem, having had two convictions for driving with an excess breath-alcohol level, one for breaching a liquor ban and another for wilful damage.
Cowley had shown "very little" remorse, which Judge Cameron said was perhaps best indicated by what he told his pre-sentence report writer: "I don't take any s***."
"That really highlights the fact you're a person that hasn't come to grips with reality," Judge Cameron said.
Cowley was sentenced to seven months' home detention, with six months of post-detention conditions, ordered to pay $1000 for emotional harm and given a warning under the three-strikes law.