Ulm, Germany - An 18-year-old sleepwalker, who climbed out of his own bedroom window while asleep, has died of his injuries after falling seven storeys, German police said on Wednesday.

His family, who had worried for years about his disorder, called emergency services personnel at 5am on Tuesday in the southern German city of Ulm after finding the youth seriously injured on the ground.

Police said the teenager seemed to have opened the seventh-storey window and simply stepped over the edge. He died in hospital on Tuesday evening.

Sleepwalking, or somnambulism, is a condition where people, most often children and teenagers, leave their beds and move around with their eyes open while in a sleep-like state. - Sapa-dpa