THE battle of the baby gurus has reawakened with research claiming that leaving little ones to cry themselves to sleep can stunt their brain development.

Verity is only updating a method from the 1950s, as espoused by a New Zealand doctor, Frederic Truby King, based on the belief that children subject to a strict routine are more likely to thrive than those who are not — those my mother refers to dismissively as “free-range” kids.