Babies who are able to “resettle” themselves after waking up are more likely to sleep for longer periods of time, according to a new study published in the Journal of Developmental & Behavioral Pediatrics.
“Infants are capable of resettling themselves back to sleep by three months of age,” said Ian St. James-Roberts and colleagues at the University of London. “Both autonomous resettling and prolonged sleeping are involved in ‘sleeping through the night’ at an early age.”
For the study, the researchers used infrared video cameras to record 101 infants overnight. Videos made at five weeks and three months of age were analyzed to determine changes in sleep and waking during this age span, a time when parents hope their baby will start sleeping more at night, while crying less.
The researchers looked for moments when the infants woke up but were able to “resettle autonomously,” or go back to sleep without parental involvement. The video footage was then compared with parental questionnaires on their infants’ sleep behaviors.
The clearest developmental progression between video recordings was an increase in length of sleep from a little over two hours at five weeks to 3.5 hours at three months. Only about 10 percent of infants slept continuously for five hours or more at five weeks, compared to 45 percent at three months.
At both ages, about one-fourth of the infants woke up and resettled themselves without parental help at least once during the night. These babies were able to fall back asleep with little or no crying/fussing.
“Self-resettling at five weeks predicted prolonged sleeping at three months,” the researchers write. Sixty-seven percent of infants who resettled in the first recording slept continuously for at least five hours in the second recording, compared to 38 percent who could not resettle.
Infants were more likely to suck their fingers or hands at three months compared to five weeks. Infants who slept through the night at three months spent more time sucking their fingers or hands, a self-regulatory strategy that may help them initiate or maintain sleep.
Prior research has shown that breast-fed infants wake up at night because they need to eat frequently. However, the new results showed no difference in resettling or sleep times for infants fed breast milk versus formula.
Previous video studies have shown that what parents call “sleeping through the night” is a misnomer; older babies who sleep through the night not only sleep for longer periods, but also are able to resettle themselves after waking.
The new study confirms that some babies develop this resettling ability in the first three months of age.
“Findings indicate the need for studies of how arousal, waking, and resettling develop into sustained sleeping, and of how environmental factors support these endogenous and behavioral processes,” said St. James-Roberts.
“If they fulfill their promise, the findings may eventually help to resolve the puzzle of why so many healthy infants should be diagnosed with sleep problems, as well as helping the families involved.”
Source: Wolters Kluwer Health