Infants who have persistent difficulties with sleep during the first year of their lives may be more likely to experience anxiety and emotional disorders during childhood, recent research suggests.

Around one in five infants aged up to 12 months have sleep difficulties, such as trouble falling asleep without the help of a parent and waking a lot during the night.

While these difficulties have been linked with poorer mental health in early childhood, until now, it was not clear whether they persisted into older childhood as well.

Australian researchers decided to investigate this further. They used data from a long-term study involving over 1,500 first-time mothers and their children.

Details on sleep patterns were gathered when the infants were three, six, nine and 12 months old, and their mental health was assessed at four and 10 years of age.

The researchers noted that 25% of the children had settled sleep patterns when they were under the age of one, while 56% had moderate, fluctuating patterns. Some 19% had persistent severe sleep difficulties.

The study found that disturbed sleep patterns were linked with an increased risk of childhood anxiety and emotional issues. In fact, those with severe difficulties were almost three times more likely to have symptoms of emotional problems when they were four years of age compared to those with settled sleep patterns.

Furthermore, they were more than twice as likely to have an emotional disorder by the age of 10. Such disorders included panic disorder, obsessive compulsive disorder, depression or bipolar disorder.

Overall, those with persistent and severe sleep problems were more than twice as likely to be generally more anxious, to have separation anxiety, and to fear getting physically hurt by the age of 10.

The researchers acknowledged that the study is observational, so cannot establish cause, however they said the findings echo those of other studies.

"Persistent disturbed sleep during infancy may be an early indicator of a child's heightened susceptibility to later mental health difficulties, in particular, anxiety problems.

"Infants with persistent severe sleep problems should be monitored for emerging mental health difficulties during childhood," the researchers from the Murdoch Children's Research Institute concluded.

Details of these findings are published in the journal, Archives of Disease in Childhood.