Ritchie Centre for Baby Health Research

Paediatric sleep

As infants and children spend the major part of their life in sleep, it is vital to understand the important role that sleep plays in normal development. In babies, between birth and six months of age there are dramatic changes occurring in sleep patterns and this is also the time when the risk of Sudden Infant Death Syndrome (SIDS) is greatest. In older children disrupted sleep has been linked to poor school outcomes and behaviour. Scientists and clinicians working in the Paediatric Sleep Group within the Ritchie Centre are researching physiological responses during sleep at different stages of child development to further understand mechanisms involved in SIDS and the effects sleep problems in children.


Sudden Infant Death Syndrome (SIDS)
Failure to arouse from sleep is believed to be one of the mechanisms involved in SIDS, but why this affects some infants and not others is still unknown. Ritchie Centre scientists are investigating arousal in infants and how the major risk factors for SIDS, such as sleeping in the prone position, maternal smoking and prematurity alter arousal pathways.

Prone sleeping is a major risk factor for SIDS, but the reasons why are also still unknown. Previous studies have shown that the control of heart rate and breathing is immature at birth, placing infants at risk of cardio-respiratory disturbances, and that this risk is highest during sleep. As Ritchie Centre scientists have previously shown arousal is impaired when infants sleep prone, their next step is to examine the effect prone sleeping has on heart rate, blood pressure control and brain oxygen levels using new state of the art non invasive techniques.


Development of cardiovascular control during sleep in preterm infants
In an infant’s first six months of life, there are dramatic developmental changes in heart and blood pressure control systems. This affects the ability to compensate for a drop in blood pressure (hypotension) or reduced blood oxygen levels (hypoxaemia). Premature infants are at an increased risk of hypoxaemia, which can lead to death. This risk is significantly greater during sleep than during wakefulness. The reason for this is still unknown, but Ritchie Centre scientists are examining the ability of infants to respond to stress during sleep in a bid to understand how and why these dangerous conditions occur, and if these conditions leave any long-lasting effects on premature infants.


Sleep disordered breathing in children
Breathing disruptions during sleep in children are very common, with snoring affecting up to 35%. The mildest form of sleep disordered breathing (SDB) is primary snoring, but children, like adults can also suffer from obstructive sleep apnoea which is associated with prolonged pauses in breathing, low oxygen levels (hypoxaemia) and sleep disruption. The term SDB encompasses this spectrum of disorders and has been associated with increased behavioural problems and poor school performance in children. There is now some evidence that, as in adults, SDB is associated with increased blood pressure, and this could increase the risk of cardiovascular disease later in life. In studies funded by the National Health and Medical Research Council of Australia we are currently using novel techniques to record blood pressure continuously overnight in children referred to the Melbourne Children’s Sleep Unit for assessment of SDB, to further elucidate the link between severity of SDB and elevated blood pressure. In new studies we will also examine the effectiveness of treatment of SDB on blood pressure, school performance and behaviour.


Down syndrome and sleep disordered breathing
Down Syndrome (DS) is caused by an extra copy of chromosome 21 (Trisomy 21) and is the most common human genetic condition. DS affects multiple systems, resulting in both physical and cognitive problems. There is an increased incidence of obstructive sleep apnoea (OSA) in children with DS, reported in up to 60% in children with DS, compared with 1-3% in the general paediatric population. DS is associated with reduced autonomic responses during wakefulness and individuals may have a diminished response to obstructive events during sleep, making them more at risk of the adverse cardiovascular effects of OSA than otherwise healthy children. Ritchie Centre researchers have undertaken a study designed to evaluate cardiovascular and sympathetic activation during sleep in children with DS and OSA and otherwise healthy children with OSA. We aim to assess the impact of OSA on cardiovascular function and determine whether children with DS are at higher risk of cardiovascular complications.


Effects of hospitalisation on children’s sleep
Being admitted to hospital for medical treatment has been shown to affect a child’s sleep and behaviour on returning home. Previously, these effects have been ascribed to the psychological impacts of hospitalisation, but we are currently undertaking studies to investigate whether poor sleep quality or quantity in hospital might be the key determinant of post-hospitalisation problems. Using a small device, similar to a wrist watch, we are measuring sleep and wake patterns during and after hospitalisation in three groups of children having different types of medical care in hospital. Our study aims to find out the major determinants of poor sleep in children in hospital, and how these might be modified to avoid long lasting sleep disturbance and behavioural problems after hospitalisation.