Thursday, April 8, 2010

The Science of Infant Sleep Part IV: Falling Asleep versus Staying Asleep

As we wrap up this multi-part series on infant sleep, we return to some of the original questions that led us to focus on this all important area. Several of you asked us about the popular recommendation to make sure that your baby is still partially awake when you put him in his crib. Others wanted to know why babies sleep through the night once or for several weeks and then start waking again. In this post, we'll revisit the interrelationships that we talked about in the last post, but this time, we'll discuss specifically how they may affect your baby's abilities to fall asleep and then stay asleep.

Baby Sleep is Complicated

I'm a big baseball fan (now stay with me, there is a point). One of the things I really love about baseball is that with every new batter, new pitcher, and new situation, the game changes. Baby sleep is a lot like that. Babies' sleep location, their own physical and developmental characteristics, and their parents' behaviors, all interact to influence infants' sleep. And, the game keeps changing as babies grow, as parents change, and when babies sleep in different places. I wish I could give you the answer to get babies to sleep quickly and for long stretches but I continue to believe that there is no single intervention that will help all babies, or even the same baby over time, in all circumstances. Now, I don't mean to imply that there is nothing parents can do. Instead, parents should think of themselves more like the baseball batter adjusting to the pitches that are thrown to them. Some adjustments in parents' actions and in babies' environments will help babies fall asleep, others might help babies stay asleep.

Falling Asleep

Believe it or not, there is a technical term for the time it takes to fall asleep, it's called "sleep-onset latency." Most newborns fall asleep while feeding (but they wake and feed frequently!) so falling asleep becomes more of a problem for older infants, especially those who hate being drowsy. Caffeine exposure and over stimulation can be important factors that might hinder babies' ability to fall asleep. Babies who are sick or uncomfortable (as with teething) will also have problems falling asleep. Dealing with these issues (with help as needed from the doctor) can be a big help to tired parents. But, there are other babies who don't want to fall asleep even when they are not sick or overstimulated. The research we found indicates that consistent bedtime routines (lasting from 20 to 40 minutes) can help babies to wind down. Some routines include a bath, a massage, some rocking, and a story or a song. The key is for parents to be consistent with a series of pleasant and soothing activities night after night. One large study found that a routine helped babies fall asleep faster and stay asleep longer with or without putting the babies down slightly awake.

Staying Asleep

Let's get back to the "put your baby down while awake" recommendation. This suggestion is used primarily as a way to prevent babies from calling out for their caregivers if they wake at night. The idea is that babies who always fall asleep in their parents' arms won't be able to fall asleep any other way. We found several "observational" studies that found that babies who were put down awake were more likely to stay asleep. In observational studies, researchers look at things the way they are and they don't try to change anything as they do in "intervention" studies. Because the same babies who accept being put down awake may sleep longer naturally than those who fight sleep, the relationship between the slightly awake baby and longer sleep may be related more to the baby's characteristics rather than the action of putting the baby down awake. So, we need intervention studies to see if the action results in longer sleep for all babies. This is where it gets tricky. There are plenty of intervention studies that include putting babies down while they are awake but none that includes only this one action (for infants). Most of the interventions include 1) education for parents about infant sleep, 2) standardized bedtime routines, 3) putting baby down at the end of the routine awake or not, and 4) changing parents' response if the baby protests going to sleep. Some of the interventions included instructions for parents to wait to respond (letting the baby cry). In other studies, parents were told to respond by touching the baby (like putting a hand on the baby's back) but not picking the baby up. Some interventions also included white noise, music, and other changes to the sleep environment.

Ok, that's a lot to take in. What does this all mean to you, a tired parent? We'd like to end this series with a few key messages.
  • Newborns need to wake for many reasons. Get some help for this tough time.
  • A single intervention is not likely to increase sleep for all babies or permanently for any baby.
  • When trying to help your baby go to sleep faster and sleep longer, you need to consider his health, age, size and developmental characteristics, your own actions and beliefs, and characteristics of his sleep environment. How a baby sleeps is not an indicator of parenting skill.
  • There are a lot of options for parents of older babies to get more sleep. Understanding more about how babies sleep, why they wake, and how "the game changes" over time can help you make informed decisions about what steps will work best for you.

Next time: Back to your questions!


  1. You're very welcome! Thanks to all of the fans who asked such great questions about infant sleep.

  2. I am a mother of 4.5 month old twins. They are waking ALL through the night. They sleep in the same room with us due to bedroom arrangement in our home. One sleeps in his crib as he is rolling over frequently. The other still sleeps in a "nap nanny" on the floor. They get a long stretch of sleep from 9 until about 1:30 or so and then it seems as if we are up and down frequently for the rest of the night! I often "give up" and take one or the other to a rocking chair in another room. The constant falling asleep only to be awakened 30 minutes later is harder on me than simply staying awake. They are big babies. Sixteen and Seventeen pounds. I am one of those parents who wants to start sneaking cereal just to see if it will help. They have a mixed diet of 70% breast milk (pumping, not actually nursing)and 30% formula. I try to have quiet time before putting them down to bed, but can't always follow the same routine because I don't always have help due to my husband's occupation. I am desperate for some help and am thinking of hiring a "baby whisperer" to just come in and do it for me because I am always too exhausted to think clearly at this point.

  3. Wow Jacqueline, you have more than your hands full! Because we don't know your circumstances, we can't offer specific advice but we can share some general tips. You should always discuss any concerns you have with your pediatrician. First, we encourage you to get some rest before you do anything. How? Recruit family and trusted friends to let you sleep or take some long naps. Rest = better decision-making. Since your children are “big,” hunger is not likely driving their waking. Cereal will likely do nothing to help you. Your 4.5 month olds are able to sleep about 5 hours but they can’t seem to get back to sleep after the first waking. Remember, a variety of stimulation will keep your babies awake and repetition will keep them sleepy. Lights on the walls, TV on, different noises, etc may be a problem. You might want to try white noise at night and to keep stimulation to a minimum during those night feedings. Caffeine or medications? Babies don’t process caffeine as quickly as you do and you may want to try avoiding caffeine. Routines are likely to be helpful (even if they are tough) both at 9 and at 2 am. From our posts, you can tell we’d think that your “baby whisperer” would at best be a short term solution and at worst, a terrible waste of money and source of additional stress. Bottom line – get help, get sleep, work with your baby’s natural tendencies and watch for progress. Good luck!

  4. I believe you're missing a reference list...