05/27/2015 12:12 pm ET Updated May 27, 2016

Should I Let My Baby Cry to Sleep? Insights From Developmental Psychology for This Age-old Question

Mom and dad are sitting on the floor right outside the nursery as they hear their infant crying and screaming from the crib refusing to go to sleep. Although every part of the parents' being is telling them to go in and rescue their infant, they are following the orders of the pediatrician who recommended they allow the baby to cry to sleep.

I am sure every parent is able to empathize with this difficult scenario. The suggestion to let your child cry to sleep may not be that simple. Understanding the psychological background behind this dilemma can help provide parents the necessary information to make an educated decision regarding this question.

There are basically two competing theories that play a role in the dilemma of allowing a baby to cry until asleep.

First: A child is born into this world as a helpless, vulnerable, and extremely dependent being. Babies do not have the ability to do anything for themselves and hence they need others to cater to each of their needs. An infant who has someone tending to their needs in a consistent manner will begin to gradually develop a sense of trust in the world. This infant is slowly beginning to realize that whenever they are in need, whenever they cry, whenever they are hurting, hungry, or dirty, an adult enters the picture and saves the day. They begin to trust that their parents will take care of their needs. When the needs of infants are consistently met they develop a sense of trust in their parents and, by extension, the world. Developmental psychologists go even a step further and suggest that if an infant develops this sense of trust early in life, the seeds of trust are planted in this infant and for the rest of his or her life they will have an easy time trusting others.

Considering the fact that these seeds of trust, or mistrust, are planted in an individual during the early stages of infancy, regularly tending to a crying infant may help instill in them this sense of trust. On the other hand, ignoring a crying baby may unfortunately instill in the infant a sense of mistrust. Now you understand why following a pediatrician's advice to just allow your infant to cry themselves to sleep must be done with caution.

The opposing approach comes from the school of the famous behaviorists. In the infamous, grand psychological question of nature vs. nurture, Behaviorists were known to take the nurture side of this debate to the extreme. They believed that growing up we are shaped by our environment and what we eventually develop into as adults is driven by our surroundings. One major way in which the environment shapes us is through positive reinforcement; we are more likely to engage in behaviors that were reinforced. For example, if you want people to act in a certain way just give them a positive reinforcer, or a reward, for the behavior you desire and they will engage in that behavior more often.

Hence, when an infant is crying in his or her crib and you enter the room and pick the baby up the child perceives your rescue as a reward for his or her crying. You are in essence reinforcing the child's crying and the more you go in and take the baby out of the crib the more you are reinforcing the crying behavior. Therefore, if parents are looking to end the crying they should not respond to a crying baby. Instead parents should ignore the cry, not reinforcing it, which overtime will diminish the crying behaviors.

So, on the one hand, entering the room and responding to the crying baby will convey to him or her that the world is a safe and trusting place helping foster within the baby a sense of overall trust. On the other hand, if you go into the room and take the crying infant out of the crib you are reinforcing his or her crying resulting in the infant learning that crying will produce a response from you and hence will only make the baby cry more in the future.

What is a parent to do? In order to answer this question you have to ask yourself, what is your parenting goal? Is your goal just to end your child's crying or is your goal to produce a well-adjusted child? If all you are trying to accomplish is to control your child's behavior, i.e. the crying, then taking your child out of the crib when they cry will just increase their crying behavior. Don't take them out of the crib, don't reinforce their crying behavior, and "sleep train" them by letting them cry until eventually they will give up and not cry any longer. However, if your goal is to produce a healthy and adaptive child, not responding to them when they cry may be hindering your efforts in producing a wholesome and trusting child. Taking your child out of their crib when they cry conveys to your child that you are available to them and are ready to cater to all their needs. You are helping to build within your child a sense of trust in the world.

However, keep in mind that it does not take a lifetime to develop this sense of trust. At some point your child will internalize this sense of trust and from that point on their crying behavior may just be a way for them to manipulate you to take them out of the crib. And, as behaviorism tells us, when you do take them out unnecessarily you are reinforcing their crying and they are likely to cry tomorrow night as well. Unfortunately the exact age at which you can be assured that your child has developed this sense of trust and can begin "sleep training" is not definitive. At a minimum, it may take at least six months for an infant to develop this sense of trust. Therefore, if you are looking to produce a healthy and adaptive child with a solid sense of trust do not let him or her cry to sleep before the age of six months. After that, I advise to give it at least another month just in case, after all, not all children develop at the same pace, and at that time you can begin allowing infants cry themselves to sleep. Give it a few excruciating days of sitting by the door of his or her room while they cry. After a few days of not reinforcing the crying behavior the crying should end and that good night sleep you have been dreaming about can begin.