When will my baby sleep through the night?

What "through the night" actually means

Sleep researchers define it as a 6+ hour stretch, not 12 hours. By that definition, ~50% of babies sleep through the night by 5 months, ~75% by 12 months.

By age

0–3 months: 2–4 hour stretches.
3–6 months: 5–8 hours possible. Some babies still feed once.
6+ months: Most can sleep 8–12 hours with strong sleep habits.

What helps

• Full daytime calories — feed every 2.5–3 hrs through 4 months
• Consistent bedtime routine from 8 weeks
• Appropriate wake windows
• Drowsy-but-awake put-downs from 4 months
• Sleep training if night waking persists past 6 months without medical cause