Hub
Every major sleep regression from 3 months through 3 years explained. What's actually happening developmentally, how long it usually lasts, and the one thing that helps the most.
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Bedtime resistance, crib-to-bed transition, nightmares, dropping the nap, early waking, and bedtime fears are behavioral patterns rather than developmental regressions. They live in their own section.
Open the Toddler Sleep hub →Sleep regressions are almost always tied to development. A motor milestone, a cognitive leap, the maturation of sleep cycles, or the onset of separation anxiety disrupts the current pattern until your baby integrates the change. The good news: the change is progress. The harder news: sleep gets messy until it's integrated.
What's happening: Around 8-12 weeks, your baby's circadian rhythm starts to develop. The chaotic newborn sleep pattern begins reorganizing, which often shows up as a stretch of disrupted nights.
Typical duration
2-4 weeks
Most useful tip
Lean into wake windows. A 3-month-old can only stay awake 60-90 minutes before getting overtired.
What's happening: The most famous regression. Around 3-5 months, your baby's sleep architecture matures: she develops adult-like sleep cycles with brief partial awakenings between them. Babies who relied on being rocked or fed to sleep now wake fully at each cycle transition.
Typical duration
2-6 weeks (permanent change to sleep architecture)
Most useful tip
This isn't a phase that passes. The new sleep cycles are permanent. Teaching independent sleep skills now (laying down drowsy but awake) is the most effective response.
What's happening: Tied to separation anxiety, new motor skills (crawling, pulling up), and the 3-to-2 nap transition. Many babies suddenly resist bedtime, wake more at night, or stand up in the crib refusing to lie back down.
Typical duration
2-4 weeks
Most useful tip
Practice the new motor skills during awake time so they don't get rehearsed in the crib at 2 AM. Keep the bedtime routine consistent. Predictability is the antidote to anxiety.
What's happening: Often coincides with first steps, the start of the 2-to-1 nap transition, and a burst of language development. Bedtime often gets harder as cognitive growth makes your toddler more aware (and more opinionated about) what's happening.
Typical duration
2-6 weeks
Most useful tip
Hold the line on the nap for now. The 2-to-1 transition usually happens between 13-18 months. Dropping the morning nap too early can backfire.
What's happening: Driven by separation anxiety, language explosion, and toddler autonomy. Your child starts to assert preferences (which book, which pajamas, which parent) and bedtime can become a battle. Some toddlers refuse the nap entirely.
Typical duration
2-6 weeks
Most useful tip
Give controlled choices. 'Blue pajamas or green pajamas?' bypasses the power struggle while preserving your toddler's need for autonomy. Stay firm on the boundary (it's bedtime), flexible on the details.
What's happening: Tied to imagination, FOMO, potty training, the move from crib to bed, and sometimes a new sibling. Common symptoms: bedtime stalling, early waking, repeated calls for water, getting out of bed.
Typical duration
2-6 weeks
Most useful tip
Pre-empt the stalling. A simple 'tickets' system (3 tickets traded in for water, hug, bathroom) often resolves the negotiation. Stay calm and don't engage in long discussions at bedtime.
What's happening: Imagination explodes around the third birthday: monsters in the closet, fear of the dark, vivid dreams. Around the same time, many preschoolers are dropping the nap, which can disrupt the whole evening routine.
Typical duration
2-6 weeks
Most useful tip
Address fears head-on, but briefly. A nightlight, a designated 'guard' stuffed animal, and a confident 'I'll be right back' work better than long explanations that grow the fear.
A sleep regression is a temporary stretch (usually 2-6 weeks) where a baby or toddler who was sleeping reasonably well starts waking more, fighting sleep, or losing nap structure. They are almost always tied to a developmental leap. A motor milestone, a cognitive jump, a maturation of sleep architecture, or separation anxiety.
Some are well-documented (the 4-month regression is a permanent change to sleep architecture, not just a phase). Others (like the 'leap weeks' described in some popular apps) are not well-supported by sleep research. Use the age-specific ones above as your map; ignore highly specific calendar predictions.
Most regressions resolve within 2-6 weeks once the underlying developmental change settles. The 4-month regression is the exception. It's not really a phase that ends, it's a transition to a new (more adult-like) sleep pattern that's permanent. Teaching independent sleep skills then has lasting effects.
Generally no. Wait until the regression has resolved and your baby is back to baseline before starting (or restarting) any formal sleep training. The exception is the 4-month regression, where the most effective response is actually to teach independent sleep skills. That's when many families start sleep training.
Mostly no. Regressions are tied to development, and the development itself is good news. What you can do is minimize the disruption: keep wake windows age-appropriate, keep the bedtime routine consistent, don't introduce new sleep crutches you'll later have to undo, and protect sleep especially during the leap. Tracking your baby's sleep across the period also gives you a useful before-and-after view.
For babies 5 months and up
By the time a regression hits, the underlying sleep associations are usually what's breaking. DreamGenius is Kiri's personalized program built with pediatric sleep specialist Courtney Palm. AAP- and AASM-aligned, and adapts to your baby's data instead of prescribing one rigid method.
Kiri's sleep tracker shows you when your baby's patterns change, before you've lost track of what normal looked like. Logging sleep across a regression also gives you the data to know when it's actually resolving.
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