Establishing healthy sleep-wake patterns early in infancy is vitally important as sleep problems can persist. Behavioural sleep interventions such as the parental presence procedure are well established and have been found to improve infant sleep as determined by parent report. The exact nature of this improvement is, however, unclear. Sleep consolidation, sleep-state organisation, and self-soothing are thought likely to change after intervention; however, no known research has comprehensively determined which of these variables change as infant sleep changes in response to intervention. Three participants aged between 7 to 11 months who met the criteria for Infant Sleep Disturbance (ISD) were referred by a Health Centre and the parental presence behavioural sleep intervention was implemented. Parental report and videosomonography (VSG) data were used to measure sleep before and after intervention. While parental report is limited in that parents can only report what they can hear and/or see, VSG offers a tool that can be used to measure sleep-state organisation, state changes, and periods when the infant is awake and quiet. The present research found that infants’ sleep became more consolidated resulting in fewer sleep-wake transitions and night wakings. Infants who had difficulties initiating sleep on their own also demonstrated decrease in Sleep Onset Delay (SOD). Furthermore, infants were found to sleep through a greater number of sleep-state transitions and sleep for a greater duration of time before waking. Collectively this research provides some evidence that changing parental behaviours to those that promote self-initiation through self-soothing and consistency, can change sleep-state organisation and improve self-soothing.