A man has been jailed for five years after being convicted of killing his baby son by shaking him.

Wayne Acott had stayed up most of the night watching TV and playing on a computer when he caused a "catastrophic collapse" to four-month-old Mackenzie.

The 22-year-old - who had also been smoking cannabis and had toothache and a headache - was convicted of manslaughter by a jury at Maidstone Crown Court this afternoon.

The child died seven days later on January 28 last year at London’s King’s College Hospital from a "triad" of injuries - subdural haemorrhage, retinal haemorrhage and lack of blood flow to the brain, causing brain damage.

Doctors said the injuries to Mackenzie were usually associated with a high-speed car crash.

Acott, of Sunningdale Court, Square Hill Road, Maidstone, denied manslaughter, claiming he did not cause any injuries to his son.

He had been with the child’s mother Susan York, 30, since 2009. She also had a daughter, aged 10 at the time of the baby’s death.

Sally Howes QC, prosecuting, said Acott had spent the night before Mackenzie’s collapse at a neighbour’s flat watching television and playing on a computer.

He returned home at about 4.30am and fell asleep on the sofa in the living room at about 6.30am. Miss York left the flat at 8.45am to take her daughter to school.

Before she left, she put Mackenzie in his chair and made attempts to get Acott up, but he just mumbled. When Miss York left, the baby was happy and smiling, said the QC.

When she returned about 30 minutes later, she found Acott holding his son. The baby’s head was floppy and he was gasping for air. He told her: "I don’t know what’s wrong."

Miss Howes said Acott had either shaken or thrown Mackenzie onto a soft surface such as a sofa or cushion. It was frequently seen, she said, as a momentary loss of control.

"when mackenzie did not take his feed, you snapped. it was momentary but it was devastating in its circumstances, because you shook that little baby…” – judge jeremy carey

Judge Jeremy Carey told Acott the jury’s verdict had proved he was responsible for the "tragic and wholly avoidable death" of his son.

"You were indeed asleep when Mackenzie was crying and crying loudly near you, having been left by his mother in your care," he said.

"You had been asleep for more than three hours having been up most of the night. You were unhappy about being awoken and, particularly, in those circumstances you had chronic toothache.

"You had been taking drugs. I doubt that had any effect on your state of mind at 9am, but that is the backdrop to this offending.

"When Mackenzie did not take his feed, you snapped. It was momentary but it was devastating in its circumstances, because you shook that little baby."

Acott shouted from the dock: "I didn’t do anything."

The judge continued: "You threw him down and caused him appalling injuries about which this jury has heard.

"I am quite satisfied you had no intention of harming the child and what you did was an expression of your temper. That is the basis on which I will sentence.

"There was here a loss of life and that must be reflected in the sentence. I take into account that not only are you still young, but you are immature."

Judge Carey said he took into account that Acott had since served a 21-month jail sentence for robbing a pizza delivery man.

"You leave behind the inevitable trauma for a mother who has lost a child," he added.

"I have no doubt the appropriate authority will be concerned about your fitness to be a parent until you reach a level of maturity such that you will be able to control your emotions."

Wayne Acott was convicted at Maidstone Crown Court

Miss Howes said Acott’s regular cannabis use caused friction between him and Miss York. It also affected his sleep pattern and he did not go to bed at a reasonable time.

Mackenzie was born prematurely at 35 weeks in September 2010 but was otherwise "a perfectly normal baby".

Prosecutor Ken Goss, from the Crown Prosecution Service, said: "No one will ever know what happened on that fateful day.

"What we do know is that Mackenzie suffered a sudden and catastrophic collapse caused by trauma to his head, which ultimately led to his tragic death."

DI Trevor Fleming, from the Kent and Essex Serious Crime Directorate, said: "It is very sad when such a young life is ended by a parent.

"It is the case that many parents feel the strain of the early months of a new baby unfortunately it would appear this young man had a momentary lapse of control, he had before that been described as a loving father.

"A number of agencies are available to help new parents and they should not be afraid to ask for help."