The Four Month Sleep Regression

What's changing for your baby, and how to protect your own sleep while it does.

This is not a step backward.

If your baby was finally sleeping longer and now wakes every hour or two, you haven't done anything wrong.

Between three and five months, almost every baby's sleep changes for good. It's a sign of a healthy, maturing brain.

Your baby's sleep is growing up

Newborns drop into deep sleep almost anywhere. Around four months, sleep starts moving through light and deep stages, the way yours does.

It's called a regression, but it's really a progression. For many families the hardest part settles within two to six weeks.

Sleep changes shape

Every sleep cycle now ends with a moment of very light sleep. Before, your baby slid right past it.

Now they often wake fully. Adults do this too; we just don't remember it.

They notice how they fell asleep

Fell asleep feeding or in your arms, then surfaced in a still crib? It's startling.

Like waking to find your pillow gone. It isn't a bad habit. It's growing awareness.

A busy, growing brain

Rolling, grabbing, and laughing all arrive around now. Babies practice new skills in their sleep, and get distracted during daytime feeds.

Distracted days can mean a hungrier night. That's normal.

The body clock is coming online

Babies start making melatonin on a day and night rhythm at around three months, and it's still settling.

Bright, social days and dark, calm nights help it find its rhythm. Until then, short naps are normal.

What it means for your sleep

• Night wakings jump from one or two to four, five, or more.
• Broken sleep leaves you less rested than the same hours in one block.
• Shorter patience, foggier memory, more tears, from either of you.
• Lying awake even when the baby is finally asleep.
• Protecting sleep is not indulgent.Ongoing sleep loss is closely linked with postpartum depression and anxiety, in mothers and partners.

When to reach out

If low mood, anxiety, or intrusive thoughts last more than two weeks, or you can't sleep even when you have the chance, speak with your provider.

National Maternal Mental Health Hotline: 1-833-TLC-MAMA (1-833-852-6262). Free, call or text, 24/7.

Rhythm: a steady day, a steadier night

• Awake windows of 1.5 to 2 hoursBetween sleeps.
• Watch for sleepy cuesStaring, eye rubbing, turning away.
• Full, focused daytime feedsIn a quiet room if baby is distracted.
• Morning daylightA walk outside helps set the body clock.
• The same short bedtime routineBath, feed, song, bed. Earlier after a day of short naps.

Environment: set the stage

• A dark roomFor naps and nights.
• Steady white noisePlayed all night long.
• 68 to 72°FWith baby in a sleep sack.
• Always on the backOn a firm, flat, empty sleep surface. Stop swaddling once baby shows signs of rolling.
• Dim, quiet night feedsKeep them calm and boring.

Practice: small chances to settle

• Pause before going inBaby may just be between cycles.
• Sometimes lay baby down drowsy but awake
• Try a hand on the chest firstA shush, or your voice, before picking up.
• Daily floor timePractice rolling while awake.
• Pick one approach for a week or twoFormal sleep training is a family choice, best talked through with your pediatrician.

Protect her sleep first

• Split the night into shiftsSo each of you gets one protected block of 4 to 5 hours.
• If she's breastfeedingBring baby to her, then take over burping, changing, and resettling.
• Earplugs or a separate roomFor whoever is off duty.
• Her daytime nap is for sleepNot for catching up on chores.
• Say yes to helpFrom family, a postpartum doula, or overnight support.

When to call your pediatrician

• Fever, fewer wet diapers, or feeding much less than usual.
• Loud snoring, gasping, or pauses in breathing during sleep.
• Crying that's unusual for your baby and can't be soothed.
• Night wakings that show no improvement after six weeks.
• Any time your instinct tells you something isn't right.

Every season of a baby's sleep is temporary.

Lower the bar on everything except rest. When this passes, your baby will be a stronger sleeper, and you'll be a stronger team.