Sleep regressions are brief periods — usually 2 to 6 weeks — when a baby or toddler who previously slept well suddenly wakes more, fights naps, or needs extra comfort. They often appear around known developmental milestones such as rolling, crawling, walking, or language bursts. This sleep regression calculator uses your child’s current age, the length of the current sleep disruption, and the specific signs you’re seeing to estimate which classic regression window best matches.
Built for tired parents, caregivers, and sleep consultants, the tool compares your input against commonly reported regression windows at 4, 6, 8–10, 12, 18, and 24 months. It returns a match-strength score, shows how strongly each window fits, and suggests what may be driving the disruption. A word of caution: sleep regressions are not a formal medical diagnosis. If sleep problems last longer than a few weeks, are severe, or are paired with breathing, pain, or illness symptoms, this tool should not replace evaluation by a pediatrician.
👶 Child's Age
Weeks are converted using 4.345 weeks per month.
⏳ Sleep disruption duration
🧩 Select the signs you are seeing
Quick-fill by age
How to Use This Tool
Start by entering your child's age in months or weeks. Then note how long the current sleep disruption has lasted — in days or weeks — and select any symptoms you're seeing from the checklist. The calculator compares your input to six classic sleep regression windows: 4, 6, 8–10, 12, 18, and 24 months. Press Check My Child's Sleep to see which window matches best, how strongly it matches, and whether your child is inside the typical window, approaching one, or past it.
Tip: For babies born more than two weeks early, many pediatric sleep consultants recommend using corrected age (age since due date) rather than chronological age when checking developmental sleep patterns.
How the Match Score Is Calculated
Each window receives two sub-scores. Age proximity measures how close your child's age is to the center of a regression window; being inside the typical range scores 100%, and the score fades gradually further away. Symptom alignment is the percentage of typical signs for that window that you selected. The overall match is weighted 75% age and 25% symptoms, so the primary driver is developmental timing, with your observations used to break ties and confirm the best fit.
Example: A 5.5-month-old with increased night wakings and very short naps would score high on both age and symptoms for the 6-month window, while a 13-month-old with the same signs might match the 12-month window better because the age fit outweighs shared symptoms.
Typical Regression Windows
These ranges reflect commonly reported patterns in private pediatric sleep support and parent surveys. Every child is unique; a regression can appear slightly early, slightly late, or not at all.
| Window | Typical Age Range | Common Signs |
|---|---|---|
| 4 months | 3.5–4.5 months | Night wakings, naps shorten, fighting sleep |
| 6 months | 5.5–7 months | Night wakings, nap changes, rolling or sitting |
| 8–10 months | 8–10.5 months | Crawling, pulling to stand, separation anxiety |
| 12 months | 11–13 months | Walking practice, separation anxiety, bedtime battles |
| 18 months | 17–20 months | Language burst, clinginess, nap refusal |
| 2 years | 22–26 months | Bedtime resistance, night wakings, big feelings |
Limitations & When to See a Doctor
Sleep regressions are a handy label for a developmental phase, not a medical diagnosis. The same symptoms can be caused by teething pain, illness, ear infection, allergies, reflux, or sleep apnea. This tool only estimates which developmental window is most likely.
See a pediatrician if sleep disruption lasts longer than 6 weeks, your child snores loudly, gasps, breathes through the mouth at night, has persistent daytime fatigue, or the change is accompanied by fever, pain, poor weight gain, or breathing trouble.
Frequently Asked Questions
How long does a sleep regression last?
Most regressions resolve in 2 to 6 weeks, but consistency with nap routines and bedtime can shorten or lengthen that window.
Can a child skip a regression?
Yes. Sleep regressions are not universal. Some children sail through a developmental leap with barely a change in sleep, while others show a clear blip at multiple windows.
What if my child's sleep doesn't improve?
If the disruption drags on beyond 6 weeks, look at schedule, sleep environment, and day sleep totals. It may be time to adjust wake windows or seek professional help from a pediatric sleep consultant or your pediatrician. The American Academy of Pediatrics' HealthyChildren website also has age-by-age sleep guidance: HealthyChildren.org Baby Sleep.