Babies with severe sleep problems suffer with more childhood anxiety, research shows.
Many babies struggle to fall asleep without a parent at their side, or wake frequently during the night - a phase that is exhausting for new parents but usually passes quickly.
However, infants with very disturbed sleep patterns could be at greater risk for anxiety and emotional issues in later childhood.
The Australian-based study primarily shows that infants with sleep problems are up to twice as likely to have anxiety-based concerns at ages four and 10 years.
The likelihood rises from about 5-15pc to about 10-25pc.
Some 1,507 first-time mothers and their babies were tracked and one in five had "persistent severe sleep problems" during their babies' first year.
Lead researcher Dr Fallon Cook, of the Murdoch Children's Research Institute in Melbourne, said: "A lot of the infants were waking up quite a lot at three months, and that's normal, but around 19pc really had persistent and severe sleep problems that were troublesome right across that first year.
"These are babies who, even by 12 months of age, are still waking three or more times during the night," said Cook. "And they might be taking up to an hour to go to sleep, and they are very difficult to settle when they wake during the night."
The mothers involved in the study described their baby's sleep patterns at three months, six months, nine months and 12 months online and in one face-to-face interview,
They were then asked about their child's mental health at four and 10 years of age.
The researchers classified the sleep patterns of a quarter of the infants as "settled," while more than half (56pc) had moderate, fluctuating sleep problems and 19.5pc had persistent severe sleep difficulties.
Those with persistent and severe sleep difficulties were nearly three times as likely to have symptoms of emotional problems when they were four years old, according to the study published in the Archives of Disease in Childhood.
They were also more than twice as likely to meet the criteria for an emotional disorder by the time they were 10.
Irish paediatric sleep expert Lucy Wolfe of Sleep Matters Clinic said: "It is also important to ensure that you do whatever you can do to help your child sleep their personal best - better sleep is proven to allow for better outcomes and lower vulnerability to anxiety, motivation and school performance.
"An earlier bedtime, predictable responses and outside activity and fresh air in lieu of screens can make a significant difference to the quality and quantity of your child's sleep.
"It is also important to understand that these results may mean that sleep issues result in later problems. But it is just as likely that sleep problems are an early indicator.
"Either way, making changes can often help an infant sleep better, and may prevent later problems with both sleep and other concerns."