A young man who was knocked out by his former friend at the Spilt Milk Music Festival has told the ACT Supreme Court of his pain and suffering.

22-year-old Jese Smith-Shields has been found guilty of assault occasioning actually bodily harm over the attack.

The victim told the court he was unable to eat solid foods for several weeks, and suffered regular headaches and night terrors as a result.

The prosecution has urged the judge to impose a jail sentence, saying a good behaviour order served in the community would not be a strong enough sentence.

Jese Smith-Shields will be sentenced next Friday.