Children whose parents used these strategies were more likely to sleep longer and have fewer bedtime behavioral difficulties, the researchers wrote in the journal Sleep Health.
"It's really hard being a parent, and we we'd like to be able to tell them which strategies to implement that will actually help," said lead study author Burt Hatch of the University of California at Davis MIND Institute in Sacramento.
About a third of infants experience sleep difficulties, such as trouble falling asleep or repeatedly waking throughout the night, the study authors wrote. These sleep problems are often associated with difficulties during later development, including anxiety, aggression and impulsivity.
"Although consistency around bedtime has always been thought to be important, there's not much data around parents implementing it or the long-term effects," he told Reuters Health by phone.
Hatch and colleagues analyzed data from a randomized controlled trial that was primarily designed to study ways to prevent infants from becoming overweight. As part of that study, parents were educated about appropriate ways to manage an infant's sleep with minimal interference. Emphasis was placed on putting infants down to sleep when tired but still awake, allowing them to fall asleep on their own without touching or feeding, providing a consistent environment for infants to sleep in, and minimizing parents sleeping with their infants on the same bed.
The research team surveyed parents during the fourth and sixth months after birth to learn how often they followed the strategies. Then, three and a half years later, they asked parents to rate difficulties with bedtime resistance, sleep initiation and nighttime waking.
About 15 percent of parents used the four strategies consistently, with younger moms more likely to use more strategies. At the same time, moms who experienced maternal depression were less likely to use the bedtime strategies.
Importantly, children were more likely to have sleep self-control by age 3 if more bedtime strategies were used and were more likely to have sleep difficulties if their mother had maternal depression. Consistent bedtime routines helped sleep duration as well.
"The most important message here is that parents can make simple changes that have both an immediate impact and long-term impact," Jodi Mindell of Saint Joseph's University in Philadelphia, Pennsylvania, told Reuters Health by phone. Mindell, who wasn't involved with this study, researches pediatric sleep disorders.
A limitation of the study is that it lacked diversity, Hatch said. This intervention was focused on one maternity hospital in New Zealand that serves mostly Caucasian, college-educated parents. These programs should be offered to higher risk groups, including different socioeconomic levels and those with a history of depression, he said.
"We often find that expectant mothers are largely focused on the birth as opposed to the many challenges that come after that process," said Liora Kempler of the Woolcock Institute of Medical Research in Sydney, Australia. Kempler, who wasn't involved with this study, researches maternal and infant sleep after childbirth, especially among first-time mothers.
Although most perinatal programs offer advice about pain relief, feeding and sleep after birth, the information is often brief or leaves room for questions, she said.
"I believe it's useful for pregnant women to educate themselves about parenting over time and how their behavior can impact their infant," Kempler told Reuters Health by email. "This not only helps them make informed decisions but gives them confidence in making those decisions, rather than being confused by the variable and often conflicting advice offered by Dr. Google and well-meaning family and friends."