Sleep regression in babies With sleep regression, just when your baby starts to develop a favorable pattern of sleep that's more predictable, everything changes.

The dreaded 4-month sleep regression is the time when your baby’s sleep patterns shift and they wake up often during the night and refuse to go back to sleep.

Sleep regression is pretty common in infants. Here, experts explain what causes sleep regression, common sleep regression ages, and more.

The consensus among sleep specialists is that there are roughly six stages of sleep regression at different ages—when the baby is 4, 6, 8, 12, 18, and 24 months old.

Sleep regressions refer to periods when a baby who previously slept well suddenly begins waking frequently, fussing more, or resisting bedtime.

The 3-month sleep regression is a common but temporary challenge that parents of infants often encounter.

Sleep regressions are a big part of that. Repeated wake-ups, crying, general fussing and an aversion to bedtime itself are all characteristics of the dreaded sleep regression.

Is your 4-month-old suddenly not sleeping as well? Here's how long sleep regressions last and why they happen.