The 18-month sleep regression: what it is and how to get through it.

Around 18 months, something shifts. A toddler who was sleeping through the night starts waking again. Naps that were reliable disappear. Bedtime, which had become manageable, turns into a battle. Parents who got through the newborn phase feeling like they'd finally cracked it suddenly feel like they're back at square one.

You haven't gone backwards. What you're experiencing is one of the most well-documented developmental shifts in early childhood — and understanding why it's happening makes all the difference.

Why the 18-month regression happens

At around 18 months, toddlers go through a significant cognitive and emotional leap. Language is exploding. Independence is developing — your toddler is becoming increasingly aware that they are a separate person from you, with their own wants and preferences. This is exciting, and it's also profoundly unsettling for them.

Sleep requires a toddler to feel safe being apart from you. When their whole developmental project is about understanding what separation means, nights become harder. It's not regression — it's growth.

How long does it last?

Typically two to six weeks. But without the right response, the patterns that develop during a regression can become habits that outlast the developmental phase itself. That's what we want to avoid.

What actually helps

• Keep the routine absolutely consistent. During developmental leaps, predictability is a toddler's greatest source of security. Bedtime should happen the same way, at the same time, every night — even when it feels like it's not working.
• Don't introduce new sleep props. If your toddler hasn't needed to be rocked or fed to sleep before, starting now because they're upset will create a new association that's hard to undo. Stay with your usual approach, with extra warmth and patience.
• Respond to connection, not just crying. A toddler waking at night at this age is often seeking reassurance that you're there. A brief, calm check-in — "I'm here, you're safe, it's sleep time" — is usually more effective than a long settling session.
• Increase connection during the day. The more secure your toddler feels with you during waking hours, the easier nights become. Extra physical closeness, one-to-one play, and positive attention during the day directly reduces night-time anxiety.
• Adjust nap timing if needed. Many 18-month-olds are transitioning to one nap or shifting nap timing. If the nap is too late or too long, it can push back bedtime and fragment night sleep. Experiment with capping the nap at 90 minutes and keeping it before 2pm.

When to get support

If you're four weeks into the regression and things aren't improving, or if sleep was already difficult before this phase, it's worth talking to someone. What looks like a regression is sometimes a deeper sleep association or scheduling issue that won't resolve on its own.

Written by Camille Le Boulba, NHS-certified parent coach. Camille has worked with 200+ families across London. Sessions available in English, French and Spanish. Read more about Camille →