Using a dummy could protect babies from cot death, according to new Australian research.Newborns who suck on dummies are less likely to die of Sudden Infant Death Syndrome because they have better cardiac control, the research suggests.And scientists at the Monash Institute of Medical Research in Clayton found that the protective effects of the dummy remain even after it has fallen out of the sleeping baby’s mouth.Associate Professor Rosemary Horne told ABC Science that previous studies have shown that using a dummy reduces the risk of cot death, however, she added that until now no one has been clear as to why this is the case.Professor Horne explained that cot death is probably caused by the failure of the baby to wake itself up if its breathing stops, or if it experiences a dramatic fall in blood pressure.Therefore, she believes that sucking a dummy must work either by increasing the baby’s chance of waking up or by improving its cardiac control – its ability to regulate its heart rate.The professor then drew the conclusion that it must improve cardiac control as it would be counterintuitive to assume that a dummy increases arousal when it is given to a baby to help it get to sleep.To test her hypothesis, Professor Horne and her team studied 37 healthy babies during daytime naps.They found that babies who were using a dummy had more variation in their heart rate, which is a sign that their cardiac system was responding to changes in their blood pressure.This applied even at times when they were not actually sucking on the dummy.However, further research is required as Professor Horne told ABC Science: ‘I don't think heart rate variability is the full story.’Professor Horne does not yet know why it is that sucking a dummy improves a baby’s cardiac control.The NHS acknowledges that using a dummy at the start of sleep can reduce the risk of cot death.However, it says that there is not strong evidence to encourage the promotion of dummy use.It says that a baby should not be given a dummy until breastfeeding is well established, at about one month old, and that its use should be stopped when the baby is between six and 12-months-old.Sudden Infant Death Syndrome is the sudden and unexplained death of an apparently healthy baby.In the UK at least 300 babies die from it each year with the most deaths occurring in babies under three-months-old.Those born prematurely or with low birth weight are at greater risk, as are baby boys.Most cot deaths occur at night and the exact cause is not known.