Does Sleep Training Cause Regressions? (And How to Avoid Setbacks)

You’re tired of hearing “just wait it out” when nights are wrecked and regressions hit like a tidal wave. One of the questions I get most often from parents considering sleep training is: “Will this make regressions worse?” Or, “If I teach baby to sleep independently, will every change be harder to manage later?”

Let’s get real: regressions are part of babyhood. They show up at developmental milestones, growth spurts, teething, transitions, travel. But doing sleep training doesn’t have to make them worse, in fact, with good preparation and the right mindset, it can make your system more resilient to those bumps.

Let’s unpack what regressions are, what the evidence says about sleep training + regressions, and how you can minimize disruption when your baby’s brain decides to throw a curveball.

What is a sleep regression, really?

A “sleep regression” isn’t a medical diagnosis, it’s a parent shorthand for a period when your baby starts waking more, naps shorten, bedtime becomes a struggle, or everything feels off. Common regression windows include:

• ~4 months

• 8–10 months

• 12 months

• 18 months

• 24 months

• Transitions (like from 3 → 2 naps)

These happen because babies’ brains are doing big developmental work (motor skills, cognition, separation awareness) all of which can temporarily disrupt sleep. Many regressions last one to two weeks if you maintain consistent habits.

Regressions are not caused by sleep training. They are part of development. But yes, they can make your training feel like it’s “broken” if you haven’t built resilience.

What the research says: does sleep training cause regressions?

Short answer: there is no strong evidence that sleep training causes more regressions or makes them worse long term.

• A review in PMC (Korownyk et al.) showed that sleep training interventions improved infant sleep compared with no intervention, and noted no adverse effects in those studies. PMC

• ParentData’s article on “Is There a Best Method for Sleep Training?” argues that sleep training programs generally improve parent well-being, reduce depressive symptoms, and show no long-term negative impact on children. ParentData by Emily Oster

• Critics of sleep training methods often overstate risks; many claims of damage or worsened regression are anecdotal, not backed by randomized trials. Scientific American+1

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One perspective you’ll find on parenting forums: some parents say they “never experienced regressions with our sleep-trained baby.” Reddit That doesn’t prove causation either way, but it does highlight that regressions aren’t a guaranteed fallout.

From what I see working with families: the real risk isn’t training, but inconsistency, throwing out structure, or reverting back to habits (rocking, feeding to sleep) when regression hits.

Why regressions might feel worse after sleep training

Even though training doesn’t cause regressions, there are reasons why they might feel worse if you’re sleep training (or newly trained):

• When baby is leaning on support (less rocking, feeding, holding), any disruption is more noticeable.

• Your expectations shift: a small regression feels bigger if you’ve been in a rhythm.

• You may “undo” training by reverting to old habits (rocking, holding all night) out of desperation, which confuses baby more.

• Regression often comes with other challenges (teething, illness) that amplify the disruption.

So setting yourself up for resilience is key.

How to reduce regression disruption (your anti-setback strategy)

Here’s what I coach families to do so regressions don’t feel like full-blown disasters:

1. Build a strong foundation first. Before starting training, ensure day habits are solid: consistent naps, good wake windows, a calming bedtime routine, light exposure, etc. That gives you buffer room when regressions arrive.

2. Use flexibility windows. Plan for a ±15–30 minute buffer on naps or bedtimes during regression periods. Don’t beat yourself up for small shifts.

3. Don’t abort your plan too soon. Most regressions resolve in a week or two. If you keep consistent (within reason), you usually regain ground faster.

4. Anticipate regressions & offer extra support. For example, when entering known regression windows (4 months, 8–10 months), be extra vigilant: limit overtiredness, shorten wake windows if needed, pack in more reassurance.

5. Use gentle modifications. During regressions, you might temporarily increase comfort (brief check-ins, extra soothing), but keep the end goal in view. Don’t fully abandon the sleep habits you’re building.

6. Log trends, not nights. If one night is rough, don’t let it break your confidence. Watch 5–7 night averages, not single nights.

7. Normalize the pushback mindset. When regressions strike, remind yourself: this is part of baby’s growth. It's not failure.

What to tell your nervous heart

When parents fear regressions from training, a few truths anchor us:

• Sleep training doesn’t cause regressions, developmental changes do.

• Having systems in place (routines, sleep structure) gives you tools to bounce back, rather than feeling shattered.

• You can weather regressions better when training is done with responsiveness and clarity, not panic or reverting.

• Regression periods are opportunities to refine your system, not ditch it.

If you’d like help customizing a regression buffer plan for your baby’s age and personality, that’s exactly part of what I do inside Raising Happy Sleepers.