Interactive above: tap on your child's age to find out what the average amount of sleep is.
Babies aged four to six months sleep an average of 14 hours a day, which drops to 10 hours by the age of nine years, a snapshot of children's sleep patterns has revealed.
A study by researchers at the Murdoch Childrens Research Institute looked at the sleep patterns of 10,000 Australian children, including how many hours they slept each day, how often they woke during the night, and their bedtimes.
Lead researcher Anna Price said the aim was to provide accurate, age-specific data on children's sleep, which researchers will analyse to determine whether there are links to mental and physical health.
"Whether a child is getting enough sleep or how much sleep a child needs is a major concern to many parents," Dr Price said. "In this study we found there is a wide range in 'normal' child sleep from four months to nine years old."
The study, published in the Archives of Disease in Childhood, found sleep time over a 24-hour period fell from an average peak of 14 hours for four to six-month-olds to 10 hours for nine-year-olds. This is mainly due to progressively later bedtimes, shifting from 8pm for babies to 9pm for older children. Older children also sleep less during the day and wake less during the night.
But Dr Price said there was wide variation in sleep patterns even within each age group. Babies aged four to six months had anywhere from 10 to 18 hours' sleep over a 24-hour period, while nine-year-olds had between six and 14 hours' sleep.
"This is what is happening with children's sleep now, and the next step is to find out if there is an optimal amount of sleep that is best for children's behaviour and health," she said.
Dr Price said sleep problems were most common with young babies, and typically involved them having trouble getting to sleep and waking frequently during the night. Problems often occurred because children had become accustomed to having a parent with them as they fell asleep, and needed help learning to fall asleep on their own.
Cale Wilkinson said he and his wife Amilia struggled to find good information about babies' sleep after the birth of eldest son Curtis, now 7. Curtis woke three or four times a night as a newborn and would take about 45 minutes to resettle and fall back to sleep, prompting a quest for answers by his parents.
Mr Wilkinson said they wondered if it was "his milk or his food or the crack of light coming through the door" for six months before seeking help at a sleep school.
"Sleep and food are the two most important things for young babies, and to have a sense that we weren't doing the right things to get him to sleep was really anxiety-inducing," he said. "Even across our three kids there is wide variation in terms of what is normal; they really are individuals in their sleep patterns. But as a first-time parent, you don't know that."
Check out the Essential Baby forum to chat to other parents about children and sleep.