There's bad news for exhausted new parents craving more shut-eye -- you can't just assume that your baby's sleep problems are normal and will soon pass.
A US study published in the journal Pediatrics found that babies with sleep issues are several times more likely to still have difficulties when they are toddlers compared to babies who sleep well.
Researchers from Cincinnati Children's Hospital Medical Center in Ohio found that one in 10 children under age three has a sleep problem like nightmares, wakings, trouble falling asleep or an inability to sleep in the child's own bed -- results within the range of other studies.
"Oftentimes the message is, 'Don't worry about Susie, this is typical and it will get better,'" said lead author Kelly Byars, a pediatric psychologist.
But her team found, and other experts agreed, that frequently it doesn't.
Sleep problems "definitely start early, and (the researchers) showed that sleep problems persist over years," said Lisa Meltzer, a pediatric sleep specialist at National Jewish Health in Colorado, who was not involved in the study.
"Children don't outgrow sleep problems, and their data shows this quite clearly."
The researchers surveyed more than 250 mothers about their children's sleep behaviors when the children were six, 12, 24 and 36 months old.
If the children started out with no sleep problems, chances were good that none would develop, the study found.
But 21 to 35 out of every 100 children with a sleep problem continued to have issues later on.
The researchers also found that the types of sleep problems shifted as the children grew older.
When the children were under two years old, the most common issues reported included trouble falling and staying asleep. At age three, the children more frequently had nightmares and restlessness.
While formal sleep disorders are considered more medically serious, Byars said that sleep problems can have an impact on children's mood, attention, learning and development -- not to mention the sleep of parents.
"Sleep needs to be a priority for the entire family. Parents need to have consistent bedtimes, wake times and consistent bedtime routines. Research has shown that all those things are very important," Meltzer said.