They're the latest must-have for exhausted new parents desperate for a good night's sleep.
Baby whisperers have become big business as parents fork out hundreds of dollars for support in getting their young ones to bed.
But some experts say sleep consultants are trying to fix perceived problems that are normal infant sleep patterns.
And they even warn that some methods could be damaging to young children.
Today we cover the business of sleep consultancy to explore what some say is a middle-class cachet on par with buying the most expensive stroller in the shop.
Emma Purdue, who runs the country's biggest consultancy, Baby Sleep Consultant, says she is filling a gap in the market for parents who want something more personalised than they can get through the healthcare system of midwives and Plunket visits.
Trying to enforce a blanket rule is unhelpful and leads to more "mummy guilt", she says.
"Simply telling all parents that there is a blanket rule around night wake ups, and that they are normal for 12 months, is not helpful, supportive, or empathetic."
She is at odds with Parents Centre which has warned its members to be wary of using sleep consultants.
"Parenting is about empathy and attention, engagement with babies. We don't see sleep consultants supporting that," says chief executive Viv Gurrey.
Professor Barry Taylor, dean of the Dunedin School of Medicine and a researcher of children's sleep disorders, encountered sleep consultants when his daughter hired one. "I got annoyed - I said 'that's my research area, why aren't you using the advice I could give you'?"
Although he believes most of the advice is available free, he also says a detailed list to work through can be a useful roadmap for frazzled parents.