If your previously decent sleeper has suddenly turned into a baby who wakes every hour, welcome to one of the most-discussed topics on UK parenting forums: the 4 month sleep regression. The good news is that it’s not really a regression at all: it’s a permanent, positive change in how your baby sleeps that just feels awful while it’s happening.
Why it happens
Around 3 to 4 months, a baby’s sleep cycles mature from the simpler newborn pattern into the same multi-stage cycle adults use, with lighter sleep and brief wakings between cycles. Newborns can often be moved or fed without stirring because their sleep is deep and undifferentiated; a 4 month old is far more easily woken between cycles, and needs to learn how to link one cycle to the next rather than fully waking each time.
What parents on forums say actually helped
A theme that comes up repeatedly is that this is the point many parents start introducing an independent settling skill, since a baby who can only fall asleep being fed or rocked will need that same input every time they surface between cycles overnight. That doesn’t mean sleep training is required: plenty of parents ride it out with more frequent night feeds or resettling and it resolves on its own within a few weeks as the new sleep pattern beds in.
A consistent, boring bedtime routine and an age-appropriate wake window (roughly 1.5 to 2 hours for most 4 month olds) come up again and again as the two things that make the biggest practical difference, more than any specific method.
How long does it last?
Most families report 2 to 6 weeks of disrupted nights before things settle into a new, if different, pattern. If sleep hasn’t improved at all after 6 to 8 weeks, it’s worth considering whether a habit has formed around the disruption (for example, needing to be fed back to sleep at every waking) that now needs addressing directly, rather than waiting for it to resolve alone.
For a full breakdown of sleep regressions at every age, safe co-sleeping guidance, and the sleep training debate, see our complete guide.
Read: Baby Sleep: The Real, Honest Guide UK Mums Actually Need →
