No Evidence of Harm
There are many historical medical and behavioral mindsets, procedures, pills and exposures that didn’t seem harmful at first… until they obviously were.
Think of: blood-letting to release bad humors from the body…
Exposures to radiation and certain chemicals such as asbestos, lead and other chemical carcinogens…
Tobacco smoking…
The list goes on.
A review of history teaches us that the absence of immediate, measurable harm or adverse effect cannot be the measuring stick that we are using to ascertain whether something is beneficial or appropriate for widespread use.
The most positive risk-benefit analysis that sleep training researchers can muster is that they find “no evidence of harm.”
That is woefully inadequate.
Especially when you take these factors into account:
1. Sleep training is, by definition, a behavioral modification. There are many well-documented potential adverse effects of applying a behavioral modification technique without understanding the underlying reason for the behavior… such as an overemphasis on external factors, negative self-perception, limited scope and reinforcement of external control.
2. Sleep training researchers could never ethically conduct a study that would truly analyze the safety and efficacy of sleep training. They would have to leave many, many babies crying alone indefinitely, for as long as it took to get data. Years. This is not conscionable to human ethics or morality.
3. Sleep training studies are notoriously short on details that actually do really matter.: What exact method was used and how consistently? What percentage of the babies in the study were breastfed vs. formula fed? What percentage of the babies were in some sort of childcare/nursery setting vs. being at home? What were the babies' temperaments and chronotype tendencies? What was the babies’ sleeping arrangement? (Hint: bedsharing and breastfeeding babies tend to be very underrepresented in the studies… which as we know these factors change babies’ and mom’s sleep architecture profoundly) There is also very clumsy cortisol measurement in available research (cortisol is sampled hours, days or weeks following the intervention) so this does not give an accurate picture as to the real-time stress effect on baby or parent.
4. Sleep training research findings are reported entirely by proxy. In other words, the actual subject of the study (the child) is not being asked directly about results. The individuals undergoing the behavioral modification technique application are not the ones being asked if they feel they are sleeping better, how it feels emotionally or physically, if they feel different during the day, etc. The parents are. The child is unable to report if they have been harmed. Research indicates that proxy respondents can tend to both over- and underestimate harm and disability, and that they are more likely to accurately report physical findings than emotional ones. It also shows that a caregiver proxy who has a high caregiving burden (for example, a tired parent with a young infant or child and a high degree of caregiving responsibility) tends to be a less reliable proxy respondent.
5. Many parents begin sleep training feeling like they have reached a vulnerable point in their mental health journey, and hope that more sleep will be beneficial. No one is arguing that long-term sleep deprivation is emotionally or mentally healthy. However, the question must be asked: is the cure actually worse than the disease? A mother’s biological impulse to respond to her child when they are in distress is absolutely fundamental, primal and undeniable. A mother ignoring that instinct because of a behavioral intervention technique, creates an internal conflict within her that in and of itself increases feelings of stress. There has never been a study that measures infant and mother’s stress levels at the moment of separation, in a responsive vs behavioral sleep intervention protocol. This seems like invaluable information to know before you promote sleep training as the answer to a mother’s declining mental health related to sleep deprivation… will this actually help or will it worsen the issue?
Our babies deserve recommendations built on the strongest possible evidence, not simply the absence of evidence to the contrary. They deserve research that reflects the complexity of infant development, honors the parent-child relationship, and asks the difficult questions that have yet to be answered.
“No evidence of harm" should not be the end of the conversation—it should be the beginning.
Infant sleep is not simply a behavior to be modified. It is shaped by biology, development, relationships, feeding, environment, temperament, and countless individual differences that cannot be reduced to a single protocol.
Every family deserves informed consent… not just the promise of more or better sleep. Every mother deserves the space to say, “this doesn’t feel right for my child or myself.”
That means honest conversations about what we know, what we don't know, and where the research has limitations. It means respecting parents' instincts alongside the evidence. And it means remembering that, throughout all of history, progress has often begun with someone who was willing to ask whether our current assumptions deserve another look.
References:
Lopez A, Tinella L, Caffò A, Bosco A. Measuring the reliability of proxy respondents in behavioural assessments: an open question. Aging Clin Exp Res. 2023 Oct;35(10):2173-2190. doi: 10.1007/s40520-023-02501-z. Epub 2023 Aug 4. PMID: 37540380; PMCID: PMC10520105.
Blunden S, Osborne J, King Y. Do responsive sleep interventions impact mental health in mother/infant dyads compared to extinction interventions? A pilot study. Arch Womens Ment Health. 2022 Jun;25(3):621-631. doi: 10.1007/s00737-022-01224-w. Epub 2022 Apr 5. PMID: 35380237; PMCID: PMC9072263.
