You finally had a good sleeper. Then, seemingly overnight, everything fell apart. If this sounds familiar, you are not alone — and you are not doing anything wrong. Sleep regressions are a normal, predictable part of infant and toddler development. Here is what is actually happening, and how to get through it.
What Is a Sleep Regression?
A sleep regression is a period — typically lasting two to six weeks — when a child who was sleeping well suddenly begins waking more frequently, resisting naps, or struggling to settle. These episodes are directly tied to developmental leaps: as the brain grows and reorganizes, sleep architecture temporarily shifts, making it harder for children to transition between sleep cycles independently.
The Most Common Regressions
The 4-month regression is the most significant because it is permanent. Around this age, infant sleep permanently shifts from two stages to four — the same adult-like cycles of light and deep sleep. Babies who relied on a prop (feeding, rocking) to fall asleep will now wake between every cycle looking for it.
Mindell, J. A., & Owens, J. A. (2015). A clinical guide to pediatric sleep: Diagnosis and management of sleep problems (3rd ed.). Lippincott Williams & Wilkins.
Between 8 and 10 months, babies develop object permanence — the understanding that things (and people) exist even when out of sight. This cognitive leap, while exciting, fuels separation anxiety and can make bedtime and overnight wakings significantly harder.
Piaget, J. (1954). The construction of reality in the child. Basic Books.
The 18-month regression coincides with a surge in language development, increased autonomy, and a growing awareness of the world. Toddlers at this stage are navigating a push-pull between independence and the need for closeness — and bedtime often becomes the battleground.
Galland, B. C., Taylor, B. J., Elder, D. E., & Herbison, P. (2012). Normal sleep patterns in infants and children: A systematic review of observational studies. Sleep Medicine Reviews, 16(3), 213–222.
How to Get Through It
Stay consistent
Your bedtime routine is an anchor. Keep it predictable — same order, same timing, same cues. Consistency signals safety to a developing nervous system.
Avoid new sleep props
It is tempting to do whatever works in the moment. But introducing new props during a regression can create habits that outlast it. Offer comfort without creating new dependencies where possible.
Give it time
Most regressions resolve on their own within two to six weeks. If sleep has not improved after six weeks, that is a signal to look more closely at sleep associations and environment — not a sign something is permanently broken.
Sleep regressions are hard. But they are also evidence that your child is growing exactly as they should. If you are in the thick of one and need support, I am here.
References
- Galland, B. C., Taylor, B. J., Elder, D. E., & Herbison, P. (2012). Normal sleep patterns in infants and children: A systematic review of observational studies. Sleep Medicine Reviews, 16(3), 213–222. https://doi.org/10.1016/j.smrv.2011.06.001
- Mindell, J. A., & Owens, J. A. (2015). A clinical guide to pediatric sleep: Diagnosis and management of sleep problems (3rd ed.). Lippincott Williams & Wilkins.
- Piaget, J. (1954). The construction of reality in the child. Basic Books.
Sam
Certified Sleep Trainer · Certified Newborn Care Specialist · Registered Psychological Associate · PsyD Clinical Psychology (Candidate). Based in San Diego, available nationwide.