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What do we know about the use of extinction (crying-it-out) with infants under 6-months?

by Macall Gordon, M.A.
(based on ongoing research as an update to work presented in 2007)

Current sleep advice emanating from pediatricians, as well as the majority of parenting books on sleep suggests that parents should start using pure extinction (put the baby in bed and don’t go in until morning), graduated extinction (progressive waiting) or time checks (waiting for set intervals) starting at 4-months (some say as early as 8 weeks) to prevent sleep problems from taking root.


A parent survey conducted in Canada on the use of graduated extinction for sleep found that more than 70% reported starting before 6-months (Loutzenhiser et al., 2014) and about 40% of those said that the approach “didn’t work at all.” The authors suggest that the lack of effectiveness in this group may be due to parents using extinction too early.

The use of extinction (crying it out) under six-months represents a significant departure from what is known from existing research, as well as from knowledge about the neurological and developmental trajectories of sleep and emotional regulation. A review of the literature on behavioral infant sleep interventions reveals that the advice to start this early is not be well-supported.

Research on the use of extinction with this age group is virtually non-existent.

Very little research has been conducted using extinction (graduated or other forms) with infants under 6-months. Indeed, one of the most seminal extinction researchers submitted that the intervention should not be used before 6-months and even then, only under close monitoring (France, 1994). A critical review of the literature on this question (Gordon & Hill, 2007) found only three studies (Eckerberg, 2004; Pinilla & Birch, 1993; Weir & Dinnick, 1988) that utilized any infants under 6-months. These studies typically sampled wide age ranges (e.g. 4- to 45- months) and did not report outcomes by age. Since 2007, studies have been conducted on younger ages, however, the type of extinction used in these studies either used extremely limited waiting periods (Crncec et al., 2010; Matthey & Speyer, 2008) or the study did not specify the length of response delay (Adachi et al., 2009; Don et al., 2002; Hiscock et al., 2014). More commonly, studies that included some infants under 6-months included them as part of a much wider sample (e.g. 4- to 52-months) and never parsed results by age; it is therefore unknown how the younger infants fared (Hall et al., 2015

Behavioral interventions in research are typically part of a larger package of interventions that include significant parent support.

A review of the more recent research on younger infants indicates that investigation has not focused on the use of extinction per se, but instead on educational interventions designed to prevent problems from taking root. Such interventions were often conducted in the context of individualized consultations and regular follow-ups with providers (Adachi et al., 2009; Matthey & Speyer, 2008; Smart & Hiscock, 2007; Stremler et al., 2013). A few studies were conducted at in-patient parenting centers where mothers received sleep information within a context of instrumental, as well as social support (Fisher et al., 2004; Matthey & Speyer, 2008). Given what is known about the impact of social support on sleep behavior (Weir & Dinnick, 1988) and the role of parental self-efficacy in outcomes (Cutrona & Troutman, 1986), it is unclear what part of the intervention was instrumental.

Further, in these studies, detail about the actual advice given about responding to nightwakings is missing – e.g. One study indicated that parents were given information about “the importance of self-soothing back to sleep” (Paul et al., 2016, p. 3), but did not provide more detail about what that meant in practical terms for parents’ behavior. Other studies merely say that education included information about normative sleep and appropriate responses to waking without further detail about what those responses should be (e.g. Santos et al., 2016).

Results of preventative studies can be modest or uneven.

In some studies, differences were seen at the end of intervention, but not at follow-up (Wolfson et al., 1992). In many cases, both intervention and control groups improved (St. James-Roberts et al., 2001). One study comparing a behavioral intervention to an educational intervention and a control group found statistical differences in the number of “uninterrupted nights” but the actual differences were small (5.79 nights vs. 5.24 and 5.22 nights; Sleep et al., 2002).

Very little is known about outcomes

Though researchers and others continue to maintain that extended crying has never been shown to be harmful, detailed investigation of this point for younger infants has not been conducted.

Claims about the lack of negative side effects of extinction can be traced to only a small number of studies (all on children over six-months) (Crncec et al., 2010; Eckerberg, 2004; France, 1992; France et al., 1991). To measure behavioral or emotional effects, researchers relied on parent report or responses to the Flint Infant Security Scale (Flint, 1974), which was originally constructed to be an early assessment of security (an early conceptualization of attachment). In fact, the results of the scale have been misinterpreted as a lack of impact on attachment. The scale itself has never been peer reviewed as an adequate measure of infant emotional or behavioral well-being.

One study (Middlemiss et al., 2012) examined cortisol levels in both mother and child (4- to 10- months) during and after an extinction-based intervention and found that even though infants appeared to go to sleep with little or no protest, their cortisol levels remained elevated. This is consistent with animal studies documenting similar findings (Coe et al., 1983). Maternal emotional availability, on the other hand has been found to be related to lower levels of cortisol, as well as better sleep (Philbrook & Teti, 2016).

Given the important brain development that occurs in early infancy, unmodulated distress (i.e. when parents let a baby cry for longer than a few minutes) may exceed their capacity to down- regulate. The regions of the brain experiencing the most rapid growth are the most vulnerable to disturbance (Webb et al., 2000). During these reorganization periods, very little stress can throw an organism off balance (Heimann, 2003; Schore, 1996). What happens, then, when a baby stops crying after extended, unmodulated distress and at an age when their capacities are limited? The ability to tolerate distress is highly maturation-dependent (Kopp, 1989; Schore, 1996) and, as a result, it is likely that infants will not experience extinction similarly across ages.

No investigation has been conducted on infants for whom extinction does not work.

While many infants will have no difficulty or disruption due to extinction, it is likely that there are many infants who cry for extended periods of time, or simply do not relent and fall asleep. To date, research has never asked “who doesn’t this work for?” A parent survey conducted in Canada on the use of graduated extinction for sleep found about 40% of parents said that the approach “didn’t work at all” (Loutzenhiser et al., 2014). A large parent survey of infants under 18-months (n=450) found about a third of parents reported no success using forms of extinction (Gordon, 2020).


Further, for temperamentally- or neurologically sensitive infants, the distress may be significant, and they may have fewer resources to be able to manage it. It is possible that extended distress and elevated cortisol in some infants, at certain points of development, or in specific family contexts may be concerning. To date, research on this point has not been conducted.

No research has been conducted on the need for intervention before 6-months.

The negative outcomes of poor sleep drive the push for behavioral sleep interventions. Indeed, while it is true that sleep problems that go unaddressed persist (Byars et al., 2012), no research to date has examined whether there are any innate benefits of starting before six-months or problems with waiting until the six-month mark. In fact, the four-month developmental regression may make intervening at this point even more difficult.


The investigation of behavioral sleep interventions to date has not taken an appropriate developmental stance. Little, if anything, is known about the effects of extinction at specific points in development or if, for some infants, extinction is contraindicated. Parents should be given a variety of effective options for sleep training, as well as information about the ranges of acceptable start times in order to make choices that fit their unique family.

Parents don’t like it (or won’t use it)

Results also indicated that parents who didn’t feel good about using extinction, had significantly less improvement and felt the process was more stressful (Loutzenhiser, Hoffman, & Beatch, 2014).

Research often discusses parental concerns about letting their children cry as merely being misinformed. Byars and Simon (2016) submit that parental concerns about harm to the infant are “unwarranted.” Researchers and others discuss the need for parental cognitive restructuring so that they don’t worry about their infants crying.


It begs the question: why do we have to try so hard to talk parents into this and is it the only way?

Time to change our thinking about sleep and sleep training

Crying-it-out is largely considered uniformly effective and the research underpinning it has failed to ask other questions: who doesn't it work for? how much crying is too much? do alternatives exist that are more palatable for parents and just as effective? Research continues to persuade parents to adopt a paradigm that is distinctly counter to how they generally think about and respond to their infants. It is time to ask different questions about sleep training and to investigate alternatives that are more consistent with the way we teach children most other skills: offer help at first and then gradually allow them to do more.


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