A sleep regression is a period when a baby who was previously sleeping well suddenly begins waking more frequently, resisting naps, or having difficulty falling asleep. Regressions are caused by developmental changes in the brain, motor skill acquisition, or emotional milestones, not by anything the parent has done wrong.
Most sleep regressions last 2 to 6 weeks. The 4-month regression is the exception: because it involves a permanent change in sleep architecture, the sleep patterns do not simply return to their previous state. Gentle sleep training after the 4-month regression is often necessary to re-establish independent sleep.
The key is to temporarily increase responsiveness while avoiding creating new long-term sleep associations. Offer extra comfort, maintain your routine as closely as possible, and use gentle settling techniques. Avoid introducing new sleep props that will need to be removed later. The Gentle Night Method includes a specific regression protocol.
Yes, and it is the most significant of all regressions. At around 4 months, the brain permanently restructures sleep architecture from newborn-style deep sleep to adult-like cycles with lighter sleep stages. This is why babies who previously slept well suddenly begin waking at the end of each cycle. It does not resolve on its own without some form of sleep support.
The developmental changes that cause regressions cannot be prevented. However, having a strong sleep foundation before a regression makes recovery much faster. Babies who have already learned to fall asleep independently tend to move through regressions more quickly than those who rely heavily on parental assistance to fall asleep.