15 Month Sleep Regression: Causes, Signs & Proven Solutions for Parents

Why does a toddler who slept peacefully last month suddenly start fighting naps, waking at night, or calling out for comfort? Parents know this shift well: the 15-month sleep regression. It shows up right when families think the rocky baby months are behind them. This stage can feel endless at 2 a.m., but it’s not. It passes. What matters most is knowing what’s happening, why it happens, and what can be done to guide sleep back on track.

What Is the 15-Month Sleep Regression?

Sleep regression at 15 months is not a medical condition. It’s a developmental bump. A toddler who was sleeping through may suddenly resist bedtime, fight naps, or wake repeatedly. Their brains and bodies are growing at full speed. Walking, talking, testing limits, all spill into rest patterns.

Pediatric reports estimate 25–50% of children face some form of sleep problems during toddlerhood. Around 15 months, it’s often linked to growth, new routines, or nap transitions. Some toddlers breeze through without much change. Others hit a rough patch that keeps the whole family awake.

Signs & Symptoms of 15 Month Sleep Regression

Parents usually notice sleep changes before realizing it’s a regression. A child who slept well begins to wake up at odd times, resist naps, or cling before bedtime. Roughly 30% of toddlers experience these kinds of disruptions at this age (Developmental Trajectories of Toddler Sleep Problems, 2022).

1. Frequent Night Wakings

That quiet stretch of rest breaks down. A toddler wakes two, three, or more times. Instead of rolling back into sleep, they cry for comfort.

2. Nap Resistance

A 15-month-old fighting naps is common. They might refuse the afternoon nap, shorten it, or skip it entirely. It’s often the start of the toddler nap transition.

3. Early Morning Rising

Some children wake before sunrise, ready to play. Parents aren’t thrilled. This often ties back to overtiredness or naps timed too late in the day.

4. Clinginess at Bedtime

Separation anxiety peaks between 15–18 months. Toddlers cling harder at bedtime, calling for parents, refusing cribs, or crying when left alone.

5. Daytime Mood Swings

A tired toddler shows it. Irritability, tantrums, or sudden bursts of energy followed by collapse are all signs that sleep is disrupted.

Causes of the 15 Month Sleep Regression

There isn’t one reason. The sleep regression at 15 months usually has several causes running together. Parents often find it’s a mix of growth, nap timing, and emotions.

1. Developmental Milestones

At this age, toddlers walk, climb, and start talking more. Their brains don’t switch off easily. Developmental milestones at 15 months make sleep lighter and more restless.

2. Nap Transition

Many toddlers are dropping naps at 15 months, moving from two naps to one. The transition takes weeks. Some days they last, other days they crash. That back-and-forth creates cranky evenings.

3. Separation Anxiety

This stage often brings separation anxiety and sleep problems. Kids want comfort at night as much as during the day. They cling, resist, and cry when left alone.

4. Teething Pain

The first molars usually break through here. Sore gums and throbbing at night mean more wake-ups. Teething and toddler sleep rarely go smoothly together.

5. Boundary Testing

Toddlers push limits. They toss toys from the crib, demand more books, or flat-out refuse to lie down. Testing boundaries is part of the game at this age.

How Long Does the 15 Month Sleep Regression Last?

It feels endless at 2 a.m., but most regressions don’t last long.

• Usually 2–6 weeks.

• Shorter if triggered by teething or growth spurts.

• Longer if tied to nap transitions or strong separation anxiety.

Consistency in bedtime routine helps shorten the phase.

What Parents Can Do to Handle a 15 Month Sleep Regression

It’s temporary. That’s worth remembering when exhaustion sets in. A structured approach helps toddlers move back into steady sleep.

1. Maintain a Consistent Bedtime Routine

Keep the pattern steady: bath, book, cuddle, bed. Same time, same order. Toddlers thrive on predictability.

2. Adjust Nap Schedule if Needed

A 15-month-old who is not sleeping well may need the toddler nap transition. Move slowly. Lengthen wake windows. Aim for one mid-day nap.

3. Create a Calm Sleep Environment

Keep the room dark, cool, and quiet. Use white noise if the house or street is loud. Avoid toys or bright lights near the crib.

4. Comfort & Reassure Without Reinforcing Bad Habits

Check in, rub a back, then leave. Long rocking or feeding every night can create new habits. Quick comfort works better long-term.

5. Address Teething & Discomfort

Talk with a pediatrician about safe relief. A chilled teether or gum massage can reduce pain. Once comfortable, sleep comes more easily.

6. Support Independence During the Day

Give plenty of play, climbing, and outside time. A busy body in the day leads to smoother rest at night.

3 Common Mistakes to Avoid During Sleep Regression

When tired, parents naturally try shortcuts. Some work briefly, others backfire.

1. Inconsistent Bedtimes

Switching schedules nightly confuses toddlers. Keep bed and nap times steady, even on rough days.

2. New Sleep Props

Rocking, holding, or co-sleeping during regression creates long-term habits. Toddlers adapt quickly to new crutches.

3. Cutting Naps Too Soon

Some 15-month-olds are ready to drop a nap; others are not. Cutting too early leads to an overtired toddler and more night waking.

When to Talk to a Pediatrician or Sleep Specialist

Most regressions resolve on their own. But call a professional if:

• Sleep regression at 15 months lasts beyond 8 weeks.

• The toddler shows growth or feeding concerns.

• Night wakings pair with unusual symptoms like fever or vomiting.

Final Thoughts

The 15-month sleep regression is real for many families. It’s tied to growth, milestones, and changing needs. It may last weeks, not months. With consistent bedtime routines, careful nap adjustments, and comfort without creating new sleep crutches, most toddlers settle again. Families who know what to expect often cope better and wake up to calmer nights.

Discover Related Topics: 9 Month Sleep Regression: What Is It and How To Handle? | The 3-Month Sleep Regression Explained