Daycare Does Not Break Children's Brains, And It Does Not Fix Economies Either

Works in Progress has published a review of the daycare literature arguing that the confident claims made in both directions are unsupported, and that whether a child attends daycare usually makes little difference to their outcomes ^[8]. If that holds, leaders writing a childcare benefit, a parental-leave policy or a return-to-office expectation have just lost the most emotive argument against them, and also the most flattering one for them.

The counter-narrative is not fringe. Mikhaila Fuller, Jordan Peterson's daughter, told her 1.3 million podcast followers that daycare affects children in "pretty nasty ways" and warned them against "traumatizing" their children ^[2]. The psychoanalyst Erica Komisar said in 2025 on Diary of a CEO that daycare makes young children more likely to develop "pathological defenses" in response to the "trauma" of separation, that "it's so bad for their brain," and that it has "been known to increase aggression" ^[3]. Komisar also suggested that separation stress makes the amygdala "become active precociously" before it "shrivels up and burns out," producing chronic anxiety, depression and ADHD ^[4]. Works in Progress calls that pure speculation, noting that nobody has done the research, and that it is not even established whether people with smaller amygdalas have them because of trauma or were born that way ^[5]. Komisar is not an outlier voice: she has contributed to the Wall Street Journal and appeared on Good Morning America ^[6].

The empirical hook for the harm argument is cortisol, and it is real as far as it goes. Children in daycare do have higher salivary cortisol, and their levels appear to rise through the day ^[7]. But cortisol is not a damage meter. It regulates metabolism and sleep-wake cycles, and with none of it in your body you would die ^[9]. In an unstressed person it peaks on waking, declines over the day, and spikes briefly in response to things like exercise and socialising ^[10]. The link between cortisol and felt stress is poorly understood, and people who report chronic stress can show lower levels ^[11]. Raised cortisol at daycare could mean a child is stressed, or that they are excited and stimulated by novelty and social complexity ^[12]. Measurement makes it worse: levels can move by an order of magnitude within a day, so the same child can produce different readings day to day, and the studies may not be powered to find a signal in that noise ^[13].

The institutional case has the same structural weakness in the opposite direction. The European Commission says preschool "lays the foundations for later success in life" ^[14]; the World Bank says it can help countries "be more productive, and compete more successfully in a rapidly changing global economy" ^[15]; governments spend billions on daycare, notionally as an investment in future workers ^[16]. Set that against a literature in which attendance usually makes little difference, and the workforce-investment framing is doing more work than the evidence permits ^[17].

The operator's conclusion is unglamorous. A childcare benefit defended as an investment in the child's brain is hostage to the next podcast episode that says the brain is being damaged; a benefit defended by what it does for an employee's ability to work, and to stay, is not. The same applies to return-to-office rules sold with developmental subtext in either direction. Works in Progress frames the test simply: if daycare had a clear effect on children, we would know by now ^[1].