You finally have a baby who sleeps through the night. You've told your friends. You've started sleeping again yourself. And then — at what feels like exactly the wrong moment — everything falls apart. Your baby is waking every two hours, your toddler is suddenly terrified of the dark, and the routine you worked so hard to build seems to mean nothing.
Welcome to a sleep regression. I've been there as a parent, and I can tell you: it passes. But understanding why it's happening makes an enormous difference to how you respond to it — and whether you come out the other side with your sleep intact.
A sleep regression is a temporary disruption in a child's established sleep patterns, typically coinciding with a significant developmental leap. The word "regression" is actually a misnomer that has unfortunately stuck — because the brain is not going backwards. It is progressing rapidly, and that rapid growth is precisely what disrupts sleep.
Think of it this way: when your brain is installing a major software update, it's harder for it to go into standby mode. Your toddler's brain is doing something similar — and at certain predictable ages, the update is so large that it interferes with the ability to transition smoothly between sleep cycles.
During periods of rapid skill acquisition, the brain undergoes intense structural changes: synaptogenesis (forming new connections between neurons), neural pruning (removing unused connections to improve efficiency), and myelination (insulating nerve fibres to speed up transmission). All of this happens most intensely during sleep — and paradoxically, it can make the brain too "activated" to transition smoothly between light and deep sleep stages.
The result is more frequent night wakings, shorter naps, resisting sleep, and sometimes an apparent reversal of all the sleep skills your child had acquired. It's temporary. The brain will settle once the developmental milestone consolidates.
Sleep architecture shifts permanently from newborn-style sleep (mostly deep sleep in long stretches) to adult-like sleep cycles with distinct light and deep phases. This is not reversible — your baby's sleep has changed permanently. The challenge: they now need to learn to independently connect sleep cycles, which they couldn't do before. Many parents find this the hardest regression because it tends to be the most abrupt and longest-lasting.
Crawling and pulling to stand are major motor achievements happening in real time. Simultaneously, babies begin to understand object permanence — the concept that you still exist when you leave the room — which paradoxically intensifies separation anxiety. The brain cannot stop processing new motor patterns even during sleep.
First steps and first words are arriving together. Many children also begin transitioning from two naps to one, creating a brief period of overtiredness while the circadian rhythm recalibrates. Night-time sleep often suffers during this transition.
Arguably the most challenging regression. Three major developmental domains collide simultaneously: a surge in autonomy and independence ("NO!"), a vocabulary explosion, and a second peak of separation anxiety. Many parents describe this period as having a different child entirely. Bedtime becomes a battleground, night wakings return, and early mornings appear from nowhere. It's real, it's recognised, and it's temporary.
The emerging imagination that makes toddlers such wonderful storytellers also introduces something new: fear of the dark, nightmares, and the beginning of emotional limit-testing at bedtime. Two-year-olds have also mastered the language to negotiate, delay, and protest — which they will deploy fully at 7:30pm.
| Age | Total Sleep Needed (24 hours) | Includes Naps? |
|---|---|---|
| Newborn (0–3 months) | 14–17 hours | Yes — no consolidated nighttime yet |
| 4–11 months | 12–15 hours | Yes — 2–3 naps |
| 1–2 years | 11–14 hours | Yes — 1 nap (by 12–18 months) |
| 3–5 years | 10–13 hours | Yes — nap optional by 3–4 years |
A few patterns I see particularly commonly in Singapore families:
Most sleep regressions resolve within 2–6 weeks if you hold the line on your existing sleep routine. The greatest mistake parents make is responding to the regression by introducing new sleep associations (feeding to sleep, bringing baby into the parental bed) that persist long after the regression has passed. Ride it out. Keep your routine consistent. The regression will end; the new habit may not.
This is counterintuitive, but important: overtired toddlers sleep worse, not better. An overstretched, overtired child produces more cortisol (the stress hormone), which makes it harder to fall asleep and increases night wakings. During a regression, if your child is struggling, try moving bedtime 30 minutes earlier rather than later. Many parents find this single change makes the most difference.
If you are in the thick of the 18-month regression, I want you to know: this is widely recognised as the most intense sleep regression of toddlerhood. It is the developmental collision of separation anxiety, language explosion, and a surge in autonomy and independence — all arriving simultaneously. It is not a parenting failure. It will end. Most families report significant improvement by 20–22 months. Validate your own exhaustion, lean on your support network, and keep the routine going.
References
American Academy of Pediatrics. Healthy Sleep Habits: How Many Hours Does Your Child Need? AAP Sleep Guidelines, 2022.
Mindell JA, Kuhn B, Lewin DS, Meltzer LJ, Sadeh A. Behavioral treatment of bedtime problems and night wakings in infants and young children. Sleep. 2006;29(10):1263–1276.
Sadeh A. Sleep assessment methods. Monographs of the Society for Research in Child Development. 2015;80(1):33–48.
Price AMH, Wake M, Ukoumunne OC, Hiscock H. Five-year follow-up of harms and benefits of behavioral infant sleep intervention. Pediatrics. 2012;130(4):643–651.