The 4-Month Sleep Regression: Why It Happens and How to Get Through It

Updated 2026-11-02 · Reviewed against the sources listed below

Your baby was finally sleeping in longer stretches, and now they are waking every hour or two again. If your little one is around 3 to 5 months old, you may be in the middle of the famous “4-month sleep regression.” The good news: it is not a step backward. It is a sign that your baby’s sleep is growing up.

What is really happening

Newborn sleep is simple: two main states, “active” sleep and “quiet” sleep, in short cycles of about 50 to 60 minutes, with roughly half the time in active sleep ^[1]. Over the next few months, that pattern reorganizes into adult-like stages of light sleep, deep sleep and dream sleep. By about 4 to 6 months, most babies have all of these stages. More stages means more moments of light sleep between cycles, and more chances to wake up fully, especially if your baby always falls asleep being fed or rocked and then wakes up somewhere different.

It is normal, and it is common

Night waking is a normal part of infant sleep. In a review of studies on healthy infants, babies under 2 months woke anywhere from 0 to about 3 times a night ^[2]. When researchers followed 75 New Zealand babies through their first year, about half were sleeping from 10 p.m. to 6 a.m. by 5 months, and most were by the end of the year ^[3]. Every baby is different, and an unsettled month around 4 months fits well within normal.

What actually helps

• Keep a short, predictable bedtime routine. In studies of young children, a consistent routine is linked with falling asleep faster and fewer night wakings ^[4].
• Put baby down drowsy but awake some of the time, so falling asleep in the crib becomes familiar.
• Keep nights dark and boring. Dim lights, quiet voices, quick changes.
• Use the same steady sound at the start of every sleep, so the room sounds the same when your baby surfaces between cycles.

A steady sound between sleep cycles

A rhythmic shush can help a baby drift back into the next cycle. Our Baby Shusher plays a slow, soft “shhh” over gentle white noise for 10 hours, with a dark screen.

How long does it last?

For many families, the roughest patch lasts a few weeks. The underlying change in sleep is permanent, but most babies learn to link their sleep cycles as they grow. If your baby seems unwell, is feeding poorly or the waking comes with fever, call your pediatrician.

Questions

References

1. Grigg-Damberger MM. The visual scoring of sleep in infants 0 to 2 months of age. Journal of Clinical Sleep Medicine. 2016;12(3):429–445. Link
2. Galland BC, Taylor BJ, Elder DE, Herbison P. Normal sleep patterns in infants and children: a systematic review of observational studies. Sleep Medicine Reviews. 2012;16(3):213–222. Link
3. Henderson JMT, France KG, Owens JL, Blampied NM. Sleeping through the night: the consolidation of self-regulated sleep across the first year of life. Pediatrics. 2010;126(5):e1081–e1087. Link
4. Mindell JA, Williamson AA. Benefits of a bedtime routine in young children: sleep, development, and beyond. Sleep Medicine Reviews. 2018;40:93–108. Link

This article summarizes published research for general information. It is not medical advice. Talk to your pediatrician about your baby’s sleep, feeding and crying.