Everybody has an opinion on sleep and sleep training in infancy. The first problem with the topic is that there is so much information and so much misinformation available to parents. The other problem with the topic is that it makes parents feel guilty and overwhelmed. Well meaning grandparent-neighbor-stranger-friend-garbage men will proceed to tell you everything that they did and everything you are doing wrong with your non-sleeping infant. [a] [b] It all leads to a terrible, no-good, horrible, sleep-deprived feeling of sleep training failure. And that sucks. You shouldn’t feel like that.
All children need to learn the self-regulatory skill of putting themselves to sleep. That is the goal of sleep training. It’s no meaner than making your child learn to tie their own shoes or do their laundry. It is a skill that is challenging, but necessary, to teach. Evidence suggests that infants who can only fall asleep with high levels of parent involvement fail to develop the ability to put themselves to sleep and will continue to rely on parents well into the toddler years. Some argue that these sleep problems can even persist into adulthood.
In my view, sleep training is not optional. Your child cannot go through life without knowing how to brush his or her teeth; nor can they go through life without knowing how to fall asleep. But, how you teach your child to sleep is a parenting decision like all other decisions (Pacifier or not? Breastfed or bottle fed? Daycare or nanny?). There are some ways to teach your child to sleep that are simply better options.
In this article, I am going to explain the parameters around sleep training, different approaches to sleep training, and what the science says about how to successfully teach your child how to sleep.
Neurologically, your child cannot be sleep trained until 4 months of age. Let me say that again. Your child cannot learn how to fall asleep on his or her own until 4 months of age. Over the first 4 months of life, children are gradually becoming used to the cycle of daytime and nighttime.[c] For the first 16 weeks children sleep about the same amount of time in each 24-hour period but they gradually shift when they are sleeping over time. Specifically, infants shift to sleeping more at nighttime than in the daytime. By the time babies are 4 months old, they sleep about twice as much as night compared to the daytime.  That’s good news. When babies sleep more at night, adults get to sleep more at night.
But beyond the neurological changes that happen in the first few months of life, socially and emotionally, your child cannot be sleep trained until 4 months of age. The first three months of life are critical for establishing a social-emotional bond between child and parent. Your child must learn that the world is a safe place. Your child needs to know that you will come if they cry. They must learn that you will hold them, comfort them, talk to them, and do your best. If you teach your child these things, you will set your child up for healthy emotional well being in infancy and beyond.
So give yourself a sleep pass for 4 months. Your job is to be sleep deprived – it just comes with the needs of your baby. Sleep when you can, take care of your body as best you can, ask for help, accept help, and love your baby. For the first four months, take your baby outside on walks or out and about to parks and stores during the daytime to help them get used to a day/night cycle. Work on setting up a loose schedule where your child eats, plays, and then sleeps.[d] Try not to let your baby fall asleep while eating, but of course, they will sometimes and don’t worry too much about that. Nap as much as you can, whenever you can. Around 10-12 weeks of age, set up a bedtime routine that is consistent and done every night. [e]
Once your child is at least 4 months of age, you can begin to consider sleep training. But you don’t have to do it right away. Maybe you are still home from work and don’t want to sleep train until you go back to work. Maybe you or your older children are sick. Maybe it’s the holiday season. Maybe you have a lot of vacations scheduled. Maybe your child was vaccinated that day – that is clearly a bad day to start sleep training. Whatever is happening in your life, you get to decide when it’s time – not the grandparent-neighbor-stranger-friend-garbage men in your life. But when you decide to do it, you have to commit to an approach and commit to being home for 2 weeks to teach the sleep routine. With #1, I went back to work at 12 weeks, but it wasn’t until #1 was 4.5 months old that I was ready to teach sleep skills. [f] With #2, I had a crazy travel schedule and couldn’t commit to being in once place until the 6-month mark. Both of those times were right for my family and me. It has to be the right time for you and your family.
While there is a clear set of reasons that you cannot teach a child sleep skills until 4 months of age, research is less clear on if there is a critical window on the other side. That is – do you have to teach your child to sleep by a certain age? By 9 months of age, there are clear differences in sleep quality in babies who know how to put themselves to sleep and those who need intervention to fall asleep (i.e., feeding, rocking, holding). Other studies have found that parental presence when children fall asleep at 17 and 29 months of age is associated with fewer consecutive sleep hours compared to kids who fall asleep alone. Presumably, the kids who fall asleep alone have had some sort of sleep training (which is why they fall asleep independently), but it’s not clear from the research design. We do know that children who never learn to sleep alone have persistent sleep problems but I can’t give you an explicit deadline of when sleep training has to happen by.
But I can tell you that sleep training an older child – such as one that can climb out of a crib – is going to be more difficult. It is well documented that when children are going through motor milestones their sleep quality decreases. Given that, I think that the best window for sleep training is sometime between 4 months and crawling (roughly 9 months).
Infant sleep experts agree that the process of shifting sleep to a long, consolidated sleep cycle at night without waking is a year long process.  For the first year of life, many infants still wake up to eat. While the long-term goal is to have a child sleep through the entire night in a 10-12 hour stretch, you may still be getting up with a baby after sleep training to feed. It’s also true that if your infant is doing really well sleeping a night, learning to crawl (see previous paragraph), getting sick, or other factors may lead to temporary shifts in sleep. Be patient with your child, and know that you are in for a full year of teaching your child this super important, life critical skill: how to sleep.
Now having said that, sleep training can see some pretty impressive, immediate results. Consistent application of sleep training for two weeks makes a strong foundation for sleep, with many babies only waking up for developmentally appropriate feedings – and it will only get better as time goes on and your child drops nighttime feedings.
So, how, exactly do you teach a child to sleep? The way that we teach children to sleep is basic behaviorist intervention – using reward (or lack of reward in this case) to give children enough time and space to figure out how to put themselves to sleep. Basically, when a child is crying for a parent to help them to go to sleep, we don’t react to the crying. While there are lots of variations in how people do it, we can categorize them in two ways: graduated extinction and full extinction.
This approach to teaching a child independent sleep habits is sometimes refereed to as check-and-console. You place your baby in their sleeping place and set a timer for a set period of time (5 minutes? 10 minutes?) and at the end of that period, you respond.[g] Most forms of graduated extinction call for responding to your child with voice and maybe a back rub but you DO NOT pick the child up or rock them to sleep. The point is for your child to learn to put themselves to sleep; Feeding, rocking, or picking them up at all would mean that you are helping them fall asleep. Gradually over time you extend the period of time before you go check on your baby. Eventually, the child learns to put him or herself to sleep. If the baby wakes up in the middle of the night (outside of what would be an age-appropriate feeding), you again wait before going in to see if the child can go back to sleep on their own.
There is another form of graduated extinction that involves picking your child up to soothe them. After a period of time of crying you pick your child up, completely soothe them into a calm state and then put them back down. Personally, I am not a big fan of it. I think it is basically a way to make parents feel better – not the baby. If you are trying to teach a child to sleep without you holding or rocking them, it doesn’t make a lot of sense to respond to a distressed child by holding and rocking. It’s teasing. If somebody was crying for a piece of cake and you came in with cake and then didn’t let him or her eat it, we would call that mean. I think picking a child up but refusing to rock them all the way to sleep (which is honestly what they are crying for) is not kind. Better to draw a hard line and communicate to your child (with your actions and words) I will not pick you up at all when it is time for you to sleep. You can be emotionally supportive without picking them up.
In this approach, you put a child into their bed and you offer no consoling to the child. Sometimes this approach is called cry-it-out. Most of the time this approach calls for a parent to leave the room and never return (or at least, don’t return until it is time for a developmentally appropriate feeding). Sometimes the approach calls for parents to sit inside the room (gradually moving their chair towards the door). Both approaches offer no consoling. This approach can be very tough on parents as crying can last for an hour (or more). This is particularly true if you are sitting in the room. Nobody likes to watch his or her child cry.
So what works? The answer is, they both do. That’s right. Consistent sleep training for a period of 2 weeks leads to improved sleep quality and sleep frequency in children. It doesn’t matter which approach you choose. What matters is that you choose one and stick with it. All approaches to teaching your child to go to sleep independently work assuming you are consistent and planful in your approach.
How do you pick? You need to take a hard look at your circumstances and evaluate which plan you will be able to successfully achieve. Do you have other obligations you must attend to that make checking in impossible? Would it be too hard on you to not check in? Would it make you too sad to be in the same room? Or conversely, not in the room at all? At the end of the day, you have to decide what is going to the best fit for your child and your family.
It is important that all people who help the baby sleep are on the same page. If you aren’t on the same page, some compromise needs to be reached. A couple I know disagreed strongly on when to sleep train. One parent was ready to do it, the other wasn’t. So, it became the job of the one who didn’t want to sleep train to do all nighttime duties. Solo. Eventually, that parent was finally ready to sleep train the child. Other families I know have worked together or compromised to come up with an approach to teaching independent sleep habits.
In my own family, I researched for weeks the scientific literature on sleep training. And I learned what you now know – they all work. We sat down and agreed on an approach and had a clear plan to enact it. But when the rubber hit the road, me, I, the one with the Ph.D. in child development, couldn’t do it. I just couldn’t handle the stress of my baby crying, even though I knew it was the best thing for both of us. I was very lucky because my partner was better at it than me. My partner did the hard work while I went and did something else. [h] So don’t fool yourself – it is a tough parenting moment. But I knew – as do you – that teaching a child to go to sleep on their own is a skill they will use their entire life. This is why it is key to wait until your child is ready, between 4 and 9 months, and you are ready.
[a] Hopefully they are well-meaning.
[b] Inevitably, some person in your social group will have a baby who sleeps through the night at 6 weeks and they didn’t do anything – “It just happened!” It’s okay to be annoyed at that person. From a scientific perspective, it is highly unusual for an infant to sleep through the night in the first few months of life and evolutionary psychologists would argue that it is not adaptive. Developmental psychology certainly tells us that most infants do not sleep through the night until nearly a year.
[c] See my article in prenatal development on sleep and wake for an understanding of why this is an extension of prenatal development.
[d]Don’t play at night. Feed and then rock right back to sleep.
[e] I always liked feed, bath, lots of lotion and smiles, book, feed, and bedtime (meaning baby is wherever the baby will spend most of the night).
[f] By ready I mean I was so exhausted I could no longer function. I sat through an entire faculty meeting and had no idea what anybody had said because I feel asleep. Obviously, something had to change.
[g] Some approaches call for sitting in the room and not responding until the set period of time. This means being totally silent during the period. From a practical perspective, it is very hard to sit in the room and watch your baby cry. See the section on full extinction.
[h] The something else I did was take a shower. I couldn’t hear the crying in there. I was the cleanest I have ever been in the first weeks of sleep training.
 Sadeh, A., Tikotzky, L., & Scher, A. (2010).
 Parmelee, A. H., Wenner, W. H., & Schulz, H. R. (1964).
 Burnham, M. M., Goodlin-Jones, B. L., Gaylor, E. E., & Anders, T. F. (2002).