A driver who is thought to have fallen asleep before his car crashed into two cars, killing a father-of-one, has been jailed for three years and four months.
Stephen Sheppard, 41, of Bournemouth, admitted causing the death of Warren Wright, 34, by dangerous driving.
Mr Wright was in the back of the car with his baby daughter when the crash happened on Wareham Road, Wool.
Sheppard suffered from sleep apnoea but had not used a machine to help the condition in the days before.
In a statement, Mr Wright's family said the primary school teacher from London was a "young man in his prime" who had "everything to live for".
Sheppard was driving a Hyundai Tucson when it collided with a caravan being towed by a Land Rover in the opposite direction on 5 July.
His car then collided head-on with a Ford Fiesta that had been travelling behind the Land Rover.
Mr Wright, a back seat passenger in the Fiesta, died at the scene. Four other injured people were taken to hospital.
Witnesses told police Sheppard's car had crossed into the wrong carriageway before the crash happened, Dorset Police said.
Sheppard was also banned from driving for five years.
Sgt Mark Scammell, of Dorset Police's traffic unit, said: "Stephen Sheppard chose to drive when he was not using the CPAP machine that he was required to use to allow him to drive safely.
"As a result of his failure to use the machine in the weeks and days leading up to 5 July 2020, it is believed he fell asleep at the wheel with devastating consequences."