Robert Harrison, 38, slept between five and six hours a night and needed "strong doses of caffeine" to do his job, Essex Police said.

His lorry crashed into 41-year-old PC Tris Baker's car on the A1060 in Roxwell, Essex on 23 September 23 2021, killing the serving children and young person officer based in Brentwood.

Harrison, from Clacton-on-Sea, was sentenced to seven years in prison at Chelmsford Crown Court on Friday after being found guilty of causing death by dangerous driving at an earlier trial.

He was also banned from driving for five years.

Essex police said in a statement: "As part of the investigation into Harrison's sleep history it transpired that he was vulnerable to falling asleep in monotonous situations such as driving on a familiar road, sleeping only between five and six hours per night and requiring strong doses of caffeine in order to carry out his day-to-day responsibilities."

Inspector Mark Fraser, who led the investigation, described PC Baker as "a much-loved family man and colleague" who is "dearly missed by those who knew him".

"My thoughts, and those of my team, are with his partner Faye and his family," he said.

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"His death was completely avoidable.

"Robert Harrison's actions were reckless and had devastating, tragic consequences and he will now face the foreseeable future in prison as a result.

"While no sentence will ever change what has happened, I hope today's outcome will bring some comfort to those close to Tris."