But it's not 1950s music these babies are listening to – more like the drones of a dishwasher or a vacuum cleaner.

The babies are taking part in trials to test a new mattress that gently rocks tots to sleep while producing sounds at the same time.

The mattress – called Easidream – has been invented by Waterlooville nursery owner and mum-of-six Lynda Harding, who struggled for years getting her children off to sleep.

The 43-year-old won a national award for her invention and now research is being carried out by Brighton University to find out if the mattress actually works.

The final product will be kitted out with a sound machine, which will produce white noise, such as the whirr of a dishwasher, to soothe the tots to sleep.

Trials have been taking place all week at Woodside Nursery School in Purbrook and the mattress really does the trick, according to parents who have volunteered their babies to take part in the research.

'My baby has been hogging the mattress,' said Jane Hale, of Liverpool Road, Fratton, Portsmouth, mother of six-month-old Isabelle.

'She's been sleeping for two hours at a time. She always likes movement anyway and falls asleep in the car.

'She has been restless, but as soon as she gets on the mattress, she nods off. It's brilliant.'

Maggie Stewart, 47, the researcher from Brighton University, is not giving anything away yet about whether the mattress works, but said it could even herald a breakthrough in the fight against cot death.

'I'm looking at a few things,' she said. 'First, do the babies go to sleep? And second, do they stay on their backs?

'The number of cot deaths has reduced enormously, but what we do know is that anything that keeps the babies on their backs is an advantage.'

Mrs Harding has been contacted by entrepreneur Rachel Elnaugh, of BBC's Dragons Den, who has agreed to help her market the mattress.

Mrs Harding said: 'Things are going really well and I am so grateful to the parents for helping out.'

n Mrs Harding is still looking for parents who would be willing to volunteer their babies for research on the sound aspect of the mattress.

Volunteers would need to play CDs with white noise, ocean sounds and heartbeats to their babies. Anyone interested should call Mrs Harding on (023) 9226 2332.