Hiscock et al. (Pediatrics, 2012): No-Long-Term-Harm Counterpoint
No detectable harm from sleep training at 5-year follow-up
Five-year follow-up of 326 families from a sleep training RCT. At child age 6, no statistically significant differences in behavior, attachment, mental health, or cortisol between the sleep-trained group and controls. The strongest counter-evidence to the harm case.
Harriet Hiscock and colleagues published a five-year follow-up study in Pediatrics in 2012 that has become the strongest counter-evidence in the sleep training debate. The team followed 326 families who had participated in a randomized trial of behavioral sleep interventions (including controlled crying) at infant age seven months.
The follow-up at age six tested behavioral problems, parent-child attachment, mental health outcomes, and cortisol patterns. The headline finding: no statistically significant differences between the sleep-trained group and the control group at age six. The Hiscock paper is regularly cited by sleep training advocates as evidence that the harm concerns have not held up at follow-up.
The methodological critiques include that the cortisol sampling was limited, attachment was measured through parent report rather than direct observation, and the sample was relatively small for the kinds of subtle long-term effects predicted by attachment theory. Both points have weight. We include this paper because the case has to engage with the strongest opposing evidence honestly.
326
Families followed
Age 6
Follow-up endpoint
0
Significant differences found
Pediatrics
Publishing journal
Why it matters
The strongest evidence that sleep training does not cause long-term harm comes from one well-conducted RCT with limitations the critics have specifically named. Both the finding and the limitations should sit in the room together.
This is one finding from the research library behind How to Birth a Mother. Everything here traces back to a study, a dataset, or a systematic review.