Baby sleep regressions by age
Check if your baby is in a sleep regression, approaching one, or between them. Covers all 5 common regressions from 4 months to 2 years.
Sleep Regression Checker
Enter your baby's age to see if they're in or near a sleep regression.
Sleep regression timeline
Five regressions happen in the first two years. They line up with major developmental changes in the brain.
4-Month Regression
3.5-5 months
Sleep cycles permanently reorganize from newborn patterns to adult-like stages. Your baby starts waking between cycles, which they didn't do before. This is the big one.
8-10 Month Regression
7.5-10 months
Crawling, pulling up, separation anxiety — the brain is busy. Babies often practice new motor skills in the crib instead of sleeping.
12-Month Regression
11-13 months
Walking, first words, and a false nap-drop signal. Your toddler might refuse the second nap, but they're not ready to drop it yet.
18-Month Regression
17-19.5 months
Language explosion, independence, and testing boundaries. Bedtime resistance and night waking are common. Often the toughest regression after the 4-month one.
2-Year Regression
23-26 months
Big transitions: new sibling, potty training, moving to a toddler bed. Sleep disruptions usually come from anxiety or overstimulation, not brain reorganization.
What sleep regressions are and why they happen
A sleep regression is a stretch of 1-4 weeks where a baby who was sleeping fine suddenly starts waking more, fighting naps, or refusing to go down. It feels like everything broke, but it's actually a sign of normal development.
Each regression lines up with a major developmental change: new motor skills, brain reorganization, language development, or growing independence. The baby's brain is working overtime during the day, and that processing spills into sleep.
The most important thing to know is that regressions end. They usually pass in 2-4 weeks without any major changes to your routine. Keeping things consistent through a regression tends to work better than overhauling the schedule.
Sources
- A Clinical Guide to Pediatric Sleep — Mindell & Owens, 3rd ed.
- Normal sleep patterns in infants and children — Galland et al., Sleep Medicine Reviews, 2012
- A longitudinal study of infant sleep — Henderson et al., 2010
Get through regressions with better data
nappi tracks your baby's sleep patterns and tells you when a regression might be affecting their schedule. Less guessing, more sleep.