My 4-month-old baby is no longer sleeping at night, what should I do?

The 4-Month Sleep Regression — It's Not Your Fault

In a nutshell: Yes, this looks exactly like the 4-month sleep regression. It's one of the toughest phases, but it's temporary and usually lasts between 2 and 6 weeks.

Why This Happens

At 4 months, your baby's brain goes through a fundamental change in their sleep cycles:

• Sleep cycles become mature — they shift from newborn cycles to cycles similar to an adult's
• Between each cycle (every 45 to 90 minutes), your baby wakes briefly and needs help falling back asleep
• This isn't a setback — it's progress in brain development

What Can Help

• White noise — mimics the womb environment and helps connect sleep cycles
• Complete darkness — blackout curtains promote melatonin production
• Consistent bedtime routine — bath, feeding, song, always in the same order
• Early bedtime — an overtired baby sleeps worse, not better
• Skin-to-skin contact — calms your baby and reduces cortisol

When to See Your Pediatrician

• If your baby seems sick (not just fussy)
• If they refuse daytime feedings
• If it doesn't improve after 8 weeks

What Other Moms Say

"It lasted 3 weeks for us. The worst part was everyone telling me to let her cry it out. I didn't, and she got through it on her own. Trust your instinct."

Remember: this phase will pass. You're doing an amazing job.

This information does not replace medical advice.