MONDAY, Nov. 12, 2018 (HealthDay News) -- If your 6-month-old still wakes up at 2 a.m., a new study suggests you don't lose any additional sleep worrying about it.
Even if she's still not getting six to eight hours of uninterrupted shut-eye at night by her first birthday, it doesn't mean your baby isn't developing normally.
And, rest assured, it probably won't hurt your child's thinking, language or motor skills later on, Canadian researchers report.
"If you've been told by your nurse or a friend that your baby should be sleeping through, on top of being tired, you probably feel like a failure," said study author Marie-Helene Pennestri, an assistant professor of psychology at McGill University in Montreal.
"Sleeping through the night is a developmental process, like walking or talking -- it's not straightforward," she added. "There's a wide variation when an infant will sleep through."
Though new parents often expect baby to sleep through the night by 6 months of age, a large percentage do not, the study revealed. In fact, many healthy, typically developing babies still don't at 12 months of age.
At 6 months old, 38 percent of babies in the study weren't yet sleeping at least six straight hours at night and 57 percent weren't staying asleep eight hours, according to their mothers' reports.
At 12 months, 28 percent still weren't sleeping six hours straight, and 43 percent weren't sleeping eight hours.
Though babies who slept through the night were less likely to be breast-fed, the study does not prove a cause-and-effect relationship, Pennestri said.
The researchers also found no evidence of later developmental lags in babies who woke at night -- and no increased risk for depression among their mothers.
"Sleeping enough is important -- everybody knows that," Pennestri said. "But there's a clear distinction between sleeping through the night and total sleep duration, which is total sleep during the night and the day. It's important to talk about sleep so parents can have more realistic expectations."
Between 4 and 11 months of age, babies need 12 to 15 hours of shut-eye, according to the National Sleep Foundation. For most, that includes two to three naps a day.
The report was published online Nov. 12 in Pediatrics.
The findings should be a wake-up call for parents who may have the wrong idea about what it means to "sleep like a baby," an Oregon pediatric sleep specialist said.
"The positive for me is it really validated that night wakenings are normal in healthy infants at age 6 and 12 months," said Dr. Elizabeth Super of OHSU-Doernbecher Children's Hospital in Portland. "It normalizes that some kids are sleeping through, but not most of them."
But the study has limitations, Super said.
For one thing, the findings are based on reports from mothers, not on objective measures of sleep such as brain waves, she pointed out.
Plus, the sample was small -- 388 6-month-olds and 369 12-month-olds -- and Super said, researchers didn't look at how their sleep habits affected their day-to-day alertness, mood or language acquisition.
Pennestri said a follow-up is underway. Among other things, it will look at breastfeeding and nighttime sleep, as well as how much sleep overall babies and mothers are getting.
Meanwhile, both Pennestri and Super urged bleary-eyed parents to relax.
Those who for personal reasons -- such as returning to work outside the home -- need their babies to sleep longer at night can ask a professional about behavioral sleep training. It includes strategies like letting baby fuss instead of responding immediately to his cries, which can help him learn to self-soothe and fall back asleep on his own.
"We can always work on healthy sleep habits," Super said.
She suggests a consistent routine for babies -- starting with a bath, massage, story or song, and a bedtime before 9 p.m. every night. For safety, always put babies on their back to sleep. Use a firm mattress and keep it free of pillows, soft bedding and stuffed toys, Super said. Light clothing is best.
The American Academy of Pediatrics recommends infants sleep in the same room -- but not the same bed -- with parents for the first 12 months of life.
Jodi Mindell, a clinical psychologist at St. Joseph's University in Philadelphia, is co-author of an editorial that accompanied Pennestri's study.
It noted that research yields no consistent answers to the question: Does sleep matter to infants?
"The answers likely depend on targeted questions that involve complex relationships and assess day-to-day functioning in young children and their families," she wrote. "Thus, the jury is still out."
The National Sleep Foundation has more about babies' sleep needs.