Infants who cry themselves to sleep in their children's beds stay just as stressed when they've stopped crying, a study has found. 'Controlled crying' is a well-known parenting method, but research published in the Journal of Early Development indicated that although youngsters may settle sooner the more often they are left to cry, their peaceful exterior is not mirrored by their internal stress levels. Hormone tests on their saliva showed that the children's levels of cortisol were just as high when they fell asleep as they were during crying, the Telegraph reported on May 24th, indicating high stress levels. Wendy Middlemiss, who carried out the study, explained that although the infants were crying for shorter periods of time, this did not mean that they were managing their feelings of distress. The study's author wrote: "On the third day of the program, results showed that infants' physiological and behavioural responses were dissociated. They no longer expressed behavioural distress during the sleep transition but their cortisol levels were elevated." However, for mothers who sat in a separate room but could hear their children crying, a drop in the stress hormone occurred in correlation to the length of time the crying continued.