She said: "These data support those parenting practices that foster children learning to go back to sleep on their own, without nursing, without being held, and eventually learn to self-comfort. This is really hard for some babies.  "And it’s even harder for parents."  However, she continued: "If parents what their children to learn to sleep through the night, they need to allow their children to learn to return to sleep after awakening.  "This may require parents to not respond when their children awaken and call out or cry, especially after nine or 10 months of age.  "If the parent knows that the child is safe and just needs help falling asleep, it may be best to let the child learn to return to sleep on their own."  She said: “The best advice is to put infants to bed at a regular time every night, allow them to fall asleep on their own and resist the urge to respond right away to awakenings.  “When mothers tune in to these night time awakenings or if a baby is in the habit of falling asleep during breastfeeding, then he or she may not be learning to how to self-soothe, something that is critical for regular sleep.”  Babies that awoke lots created “problems" for mothers "and other family members”, she said.  As a result parents of such children “might be encouraged to establish more nuanced and carefully targeted routines to help babies with self-soothing and to seek occasional respite”.  Writing in the journal Developmental Psychology, she and colleagues said they also found that mothers of babies who woke persistently were more likely to be depressed. The babies themselves were more likely to be irritable.  However, she admitted their research could not tease out cause and effect. Were their mothering techniques leading to poorer sleep and hence maternal depression? Or did pre-existing depression mean such mothers could not bear to leave their babies to cry?  Prof Weinraub's advice tallies with that of baby gurus such as Gina Ford, author of The New Contented Little Baby Book.  Ford advocates a rigid approach towards bedtimes that includes letting the baby settle alone for a time - a technique called ‘controlled crying’ - and a ‘no eye contact’ rule while settling them.  However, Ford has frequently been attacked as unloving, with critics frequently pointing out that she is a maternity nurse who has never had a child of her own.  Nick Clegg, the Deputy Prime Minister, bravely entered the fray three years ago, likening her methods to “a sort of Ikea assembly instruction manual” that advocated sticking a child “in a broom cupboard”.  For that he earned Ford’s rebuke that his comments were “sad …coming from a supposedly intelligent man”.  Proponents of 'attachment parenting' see letting babies cry themselves to sleep as a form of neglect that could lead to long-term psychological damage.  The same year Penelope Leach wrote in her book The Essential First Year: "It is potentially damaging to leave babies to cry."  It generated high levels of the stress hormone cortisol, she said, which over time "neurobiologists say is toxic to the human brain".  This May, a University of North Texas study was published bearing this out - although it was led by a member of the Attachment Parenting International Research Group.  Both sides of the debate - or rather argument - wield academic studies as weapons in a fight that is unlikely to end soon.  NHS advice errs towards controlled crying.  The NHS Choices website proposes that parents "could try" to "teach your child to get back to sleep by themselves", by leaving them for five to 10 minutes at a time.  "It might take a week or two but if you keep the routine going, your child should start falling asleep on their own," it encourages.  It adds: "Tackle it together. If you have a partner, agree between you how to tackle your child’s sleeping problems.  "You don’t want to try to decide what to do in the middle of the night. If you've both agreed what's best for your child, it’ll be easier to stick to your plan."  For some couples, such agreement is likely to be a tall order.
It will be music to the ears of those who lobby their loved-ones in vain to   &lsquo;just leave the baby&rsquo;. And it will be a red rag to those who view letting a   baby cry itself to sleep as a cruel 1950s throwback.