Troubleshooting
Sleep was great, then everything fell apart
Last updated
Your baby was sleeping through. Last night they woke twice. Tonight they fought bedtime for an hour. This guide is the diagnostic.
What is going on
Almost every “the training failed” call to a pediatric sleep specialist turns out to be one of five things. Run through them in order.
1. Developmental regression
The 8-month, 12-month, and 18-month windows. If your baby is in or near one of these and the disruption coincides with a new motor or language skill, the cause is almost certainly developmental.
The fix: a short Ferber re-arc. Most regressions resolve in two or three nights at the appropriate interval level. The regressions guide is the reference.
2. Recent illness
Even a minor cold or ear infection that has resolved can leave a behavioural residue. Your baby learned during the illness that crying brings a parent in for comfort and a possible feed. They are testing whether that is still true.
The fix: clean Ferber re-arc, two to four nights. The teething and illness guide covers post-illness restart.
3. Recent travel or routine change
A holiday, a long weekend, a new daycare, a move, a new sibling, a parent traveling for work. Any of these can disrupt the trained pattern.
The fix: hold the routine and run a short re-arc. The daycare and routine changes guide walks through specific scenarios.
4. A schedule drift
Bedtime drifted later. Naps drifted later. The morning wake is now earlier. None of these alone seems significant; together they shift the sleep architecture enough to break a previously stable pattern.
The fix: tighten the schedule. Bedtime within a 30-minute window each night. Cap naps. The early-morning wakings guide has the daytime framework.
5. A new sleep crutch you did not notice
Some parents accidentally introduce a new aid: an extra rock, a “just this once” feed, a new white noise pattern, a different blanket. Once the new aid is in, the baby starts waking when it is not present.
The fix: identify the new aid and remove it. Run a short re-arc to re-establish independent settling.
The diagnostic order
Work through these in order. Most regressions hit the first or second match and resolve.
- Has your baby reached a developmental milestone in the past two weeks? Crawling, pulling to stand, walking, language burst. If yes, this is a developmental regression. Re-arc.
- Has your baby been sick in the past two weeks? If yes, this is a post-illness pattern. Re-arc.
- Has anything changed in the household routine in the past two weeks? Travel, daycare, move, new sibling, parental schedule change. If yes, hold the routine and re-arc.
- Has bedtime, naptime, or morning wake drifted by more than 30 minutes from your baseline? If yes, tighten the schedule.
- Have you added or changed anything about how your baby falls asleep? If yes, remove the new aid.
If none of the five matches and the disruption is older than two weeks, talk to your pediatrician. There may be an ear infection, sleep apnea, or other condition that needs medical attention rather than behavioural correction.
How to do a short re-arc
The same protocol as the original arc, fewer nights. Most re-arcs run in two to four nights because the protocol is already learned.
- Pick the night in the table that matches your baby’s current time-to-asleep. If your baby was previously taking ten minutes and now takes thirty, start at Night 2 or 3 (which has 5-10-12 or 10-12-15 intervals).
- Run that night’s intervals tonight.
- Step up one row each night.
- Hold at the night that matches your previous baseline for one night.
- Resume normal life.
The Huckleberry guidance recommends this short-re-arc pattern over starting from Night 1, and it is the standard approach.
What not to do during a regression
The temptation is to undo the original training. Three common mistakes:
- Bringing the baby into bed once. They learn that calling for enough time produces this. Now the regression is permanent.
- Adding a new feeding. A baby who slept through does not need a new feed.
- Lengthening the bedtime routine. A 45-minute routine becomes the new minimum.
What the app does about regressions
The app’s history view is most useful here. A regression shows as an obvious bump on the time-to-asleep curve, often with the cause visible (a vaccination logged that day, a daycare-start in the notes, a travel pause that did not resume cleanly).
The re-arc flow lets you start from any night, with the right intervals pre-loaded. You pick the night, the timer runs.