Is “Cry It Out” Sleep Training Safe? What the New 2026 Research Actually Says

Last updated: July 2026. This article is for general information and is not a substitute for personalised advice from your doctor, health visitor, or paediatrician. See our Editorial Policy.

Quick answer: A newly published book from James Madison University professor Jennie Rosier, Dispelling Cry-It-Out Sleep Training Myths and What to Do Instead, argues that infant night waking is normal biology, not a behaviour problem — and that “self-soothing” during cry-it-out is really “self-silencing,” since infants can’t learn true self-regulation until they’ve had thousands of repeated experiences of an adult calming them first. That’s one side. On the other side, published cortisol studies cited in AAP-aligned reviews found babies’ stress hormones normalised by the end of a structured sleep-training week, with no measured difference in attachment or behaviour problems versus non-trained babies. The honest answer: the research is genuinely split, but both sides agree on one thing — consistency matters more than which specific method you pick, and no major paediatric body says an occasional cry-it-out night causes lasting harm.

Why this is in the news right now

On July 22, 2026, JMU associate professor Jennie Rosier and seven co-authors published research pushing back hard on cry-it-out, the sleep-training method where a baby is put down awake and left to fall asleep (and resettle after waking) without being picked up. Rosier’s core claim: infants biologically need to wake at night, adults expect otherwise mostly because it’s convenient for the adult, and what looks like a baby “self-soothing” into silence is often a baby giving up on getting a response — not learning a skill. She points to co-regulation (a caregiver helping a baby calm down, over and over, across months) as the actual mechanism behind eventual self-soothing, which she says isn’t fully in place until the mid-20s in humans generally.

That’s a strong claim, and it’s not the only research on the topic — which is exactly why it’s worth unpacking rather than picking a side based on one headline.

The case against cry-it-out

The most-cited research here comes from psychologist Wendy Middlemiss, who measured cortisol (a stress hormone) in babies during sleep training. Her finding: by night three, babies cried less and fell asleep faster, but their cortisol levels stayed just as high as night one. In other words, the babies looked calmer on the outside while still showing physiological stress — the crying stopped, but the underlying stress response didn’t. That’s the research basis for the “self-silencing, not self-soothing” argument Rosier and others make, and it’s a genuinely useful data point for parents who feel instinctively uneasy about extinction-based methods.

The case that structured sleep training is safe

At the same time, a frequently cited controlled study found the opposite trend over a longer window: infants in a sleep-training group had decreased cortisol by the end of training, and — critically — no measurable difference in attachment style or behavioural problems compared with babies who weren’t sleep trained. Babies allowed to cry it out also slept meaningfully longer on average. This is the research underpinning why the American Academy of Pediatrics’ First 1,000 Days guidance treats structured sleep training as a legitimate, evidence-supported option, not a harmful one — while still emphasising that parents should feel free to adapt or drop an approach that isn’t working for their family.

So which one is “right”? Here’s the honest framing

Both bodies of research are real and both get selectively quoted by people who’ve already picked a side. The more useful way to read this for your own family:

• If cry-it-out feels wrong to you, that instinct is backed by real research — the Middlemiss cortisol data is legitimate, and “my baby seems calm but I don’t trust it” is a reasonable read of that evidence.
• If you’ve done graduated or full extinction sleep training and it worked, you haven’t harmed your baby’s attachment — the AAP-aligned cortisol-normalisation and attachment-outcome data is also legitimate.
• Consistency is the actual variable that predicts success in both camps. Whatever method you choose — full cry-it-out, graduated check-ins (Ferber), the chair method, or a no-cry approach where you stay present until baby is asleep — switching methods every few nights is what tends to prolong the struggle, not the method itself.
• Age matters more than the method debate does. Most paediatric guidance still holds that formal sleep training isn’t appropriate before roughly 4–6 months, regardless of which camp you land in.

If you’re further back than the sleep-training decision and just trying to figure out what’s normal for your baby’s age, our guide on when babies actually sleep through the night covers realistic expectations by month. And if bedsharing is part of how you’re currently getting through the night, our safe co-sleeping guide covers the European paediatric safety guidance for that specifically.

Gentler alternatives, if you want to skip extinction methods entirely

If the Middlemiss research resonates with you and you’d rather not do any version of cry-it-out, these are the evidence-informed alternatives Rosier and similar researchers point to:

• Camping out / the chair method: Sit in the room while your baby falls asleep, gradually moving your chair further from the cot every few nights until you’re out of the room.
• Pick-up-put-down: Pick your baby up when they cry, soothe briefly until calm, then put them back down awake — repeating as many times as needed.
• Bedtime fading: Temporarily shift bedtime later to match when your baby is actually falling asleep easily, then gradually move it earlier once sleep is consolidating.
• Responsive settling: Respond every time, but pause a few seconds before responding to give your baby a brief chance to resettle alone first — a middle ground between full extinction and immediate response.

None of these require your baby to cry unattended, and all of them rely on the same underlying idea: co-regulation now, independent settling later.

Gear that supports whichever approach you choose

• A reliable white noise machine — useful regardless of method, since consistent sound cues help any baby resettle after normal night waking.
• A bedside co-sleeper bassinet — makes responsive, low-disruption night settling physically easier in the first few months (see our co-sleeping safety guide above for placement rules).
• A video baby monitor — lets you assess a wake-up before deciding how to respond, rather than guessing from another room.
• A weighted-free, safety-approved sleep sack — supports safe sleep positioning whichever settling method you’re using.

These fit naturally alongside the sleep-routine checklist inside parentiol’s New Parent Starter Bundle, which includes a printable night-waking log so you can actually track whether a chosen method is working after a week, rather than relying on how exhausted you feel in the moment.

The bottom line

New 2026 research from JMU makes a real, evidence-backed case that infant night waking is normal and that “self-soothing” during cry-it-out may really be a baby quietly giving up rather than learning a skill. Older, also-legitimate research shows structured sleep training doesn’t damage attachment or behaviour and does reduce stress hormones by the end of a consistent week. Neither side has “won,” and no major paediatric body is telling parents that an occasional hard night of crying causes lasting damage. What actually predicts a better outcome, in both bodies of research, is picking an approach that matches your own comfort level and sticking with it consistently — rather than switching methods every few nights out of guilt or exhaustion.