The 18 Month Sleep Regression: Why It Happens and How Long It Lasts

By Paola Mendoza, Certified Pediatric Sleep Consultant (CPSM) · Last updated October 2026

Quick answer: The 18 month sleep regression usually shows up between 17 and 19 months and lasts 2 to 6 weeks. It's driven by a big jump in independence, separation anxiety, language and often molars. Most toddlers go back to sleeping well on their own if you keep their schedule and routine steady and avoid starting new sleep habits you don't want to keep.

Your toddler was sleeping through the night. Bedtime was easy. Then one week, out of nowhere, every bedtime turns into a negotiation, the nap becomes optional and you're back in the nursery at 2:00 a.m. You didn't do anything wrong. Your toddler just hit one of the busiest developmental stretches of their first three years.

What is the 18 month sleep regression?

It's a temporary period when a toddler who used to sleep well starts resisting bedtime, fighting naps or waking more at night. It isn't a step backward. It's a sign that a lot is happening in your toddler's brain and body at the same time, and sleep is where it shows up first.

Why does it happen at 18 months?

• Independence. Your toddler just discovered they're their own person, and they want to test it. "No" becomes a favorite word, and bedtime is one of the few things they can try to control.

• Separation anxiety. It often peaks again around 18 months. Your toddler understands that when you leave the room, you're somewhere else, and they don't love it.

• Language. Many toddlers go through a word burst around this age. Their brain is working hard, and some practice their new skills in the crib at night.

• Molars and canines. First molars usually come in between 13 and 19 months, and canines between 16 and 23 months. They tend to be more uncomfortable than the front teeth.

• One nap. Many toddlers have only recently moved to one nap. If that nap is too short or poorly timed, they reach bedtime overtired. Here's how the 2 to 1 nap transition works.

How long does the 18 month sleep regression last?

Most last 2 to 6 weeks. The regressions that drag on for months are usually the ones where a new habit settled in during the rough patch: a later bedtime, a parent who now stays until the toddler falls asleep, or a bottle or show that became part of falling asleep. The regression ends. The habit stays.

How much sleep does an 18 month old need?

At 18 months	What's typical
Total sleep in 24 hours	11 to 14 hours
Naps	1 nap, usually 1.5 to 3 hours
Wake window before nap	About 5 to 6 hours
Wake window before bed	About 4.5 to 5.5 hours
Typical bedtime	6:30 to 8:00 p.m.

Want a plan built for your toddler?

The Restful Nights Plan gives you a custom sleep plan and schedule for your toddler, a live call to walk through it, and 14 days of daily messaging with me while you put it into practice. It's the plan most families choose.

See the Restful Nights Plan

Toddler 18 to 36 months? See how I help toddlers.

Every toddler is different, but if your toddler is getting a lot less than this, an overtired body is probably making the regression louder. See wake windows by age.

What helps during the 18 month sleep regression?

• Keep the schedule steady. Same wake-up time, same nap time, same bedtime. Predictable days make for calmer nights, especially when everything else feels new to your toddler.

• Protect the bedtime routine. A short, calm routine done in the same order every night tells your toddler what comes next. If you need ideas, here's how to build a bedtime routine that actually works.

• Give small choices before bed. Which pajamas, which book, which cup. Toddlers who get to make a few choices fight less about the things that aren't up for discussion, like bedtime itself.

• Fill their cup during the day. Extra one-on-one time, cuddles and play before bedtime help a toddler going through separation anxiety feel safe when it's time to say goodnight.

• Don't fall for the stall. One more book, one more drink, one more hug. Toddlers are excellent negotiators. Build water and books into the routine so the answer at the end is easy.

• Don't drop the nap. Many toddlers refuse their nap during this stretch, and parents think they're ready to drop it. Most children need a nap until somewhere between 3 and 4 years old. Keep offering it.

• Check in with your pediatrician about teeth. If your toddler seems to be in pain, your pediatrician can tell you what's safe to give.

• Be careful with new habits. In the middle of a rough night, it's tempting to do whatever works. Before you start something new, ask yourself if you'd be happy doing it every night for the next six months.

When is it not a regression?

If your toddler has been sleeping poorly for more than 6 weeks, or never really slept well to begin with, it's probably not a regression. It's usually a mix of schedule, sleep environment and how your toddler falls asleep, and that won't fix itself with time.

18 month sleep regression FAQ

Is the 18 month sleep regression real?

Yes. It isn't a medical term, but a lot of toddlers go through a rough patch around 18 months because of separation anxiety, independence, language and teething all landing at once.

Can the 18 month sleep regression start at 17 months?

Yes. It can show up anywhere from about 17 to 19 months. Every toddler develops on their own timeline.

Is my 18 month old ready to drop their nap?

Almost certainly not. Nap refusal is one of the most common signs of the regression. Most toddlers still need one nap until age 3 or later.

Should I move my toddler to a big bed to fix sleep?

Not during a regression. A toddler bed adds freedom right when your toddler is testing every limit, and it usually makes bedtime harder. Most children do best in a crib until closer to age 3.

Keep reading: The 8 Month Sleep Regression: Why It Happens and How Long It Lasts

Still fighting bedtime after six weeks?

That usually means the regression wasn't the whole story. Let's figure out what's really going on with your toddler's sleep, before you spend a dollar.

Book a Free Discovery Call