A drug-driver left another motorist "no time, hope or prospect" of avoiding a crash which killed two parents who had their children in the car.
Luke Norton, 31, killed Robert, 36, and Paula Bateman, 35, in a head-on crash on the A142 in Cambridgeshire just after 20:00 BST on 3 September.
Their daughters Lexi, 10, and 18-month-old Elizabeth survived the crash.
Norton admitted causing death by dangerous driving and was jailed for eight years and eight months.
He had also pleaded guilty to driving a motor vehicle with an excess amount of the drug benzoylecgonine, the main metabolite of cocaine, in his blood.
Peterborough Crown Court heard Norton, of Nocton Park Road, Nocton, Lincolnshire, had fallen asleep at the wheel.
Police said Norton visited a friend in Lincoln on 2 September and stayed up until the early hours of the morning taking cocaine.
The construction worker was scheduled to drive his van to Yaxley for a job, but "for reasons unknown he headed onto the A142 towards Chatteris", officers said.
Prosecutor John Farmer told the court Norton drove directly across the road and head-on into the Ford Focus being driven by Mr Bateman, which had Mrs Bateman as the rear-seat passenger behind him.
"There's only one explanation, a combination of absence of sleep, drugs, disorientation, and he disintegrates into falling asleep," he said.
"There's no steerage, there's no braking.
"He just goes across the road, into the darkness, Mr Bateman had no time, hope or prospect of doing anything."
The court was told their daughter Lexi asked a member of the public at the scene: "Is my dad still alive? Please let my mum still be alive."
Sgt Mark Dollard, of the Serious Collision Investigation Unit, said: "Many people, myself included, would struggle to think of a more truly heartbreaking case than one where two little girls lost their parents in a collision they too were involved in.
"This is yet another case which highlights the utter devastation and life-changing impact someone can cause by getting behind the wheel after taking drugs.
"Had Norton not done so, Lexi and Elizabeth could have grown up with their loving parents by their side."
Norton was also disqualified from driving for 14 years and four months.