🍼 Understanding Your Baby’s Sleep Development in the First Year

Sleep in the first year is a complex, ever-changing process that reflects your baby’s brain growth and developing ability to regulate their body, emotions, and environment. What looks like “good sleep” early on actually depends on co-regulation — the dance between caregiver and baby that helps little ones feel safe and secure enough to rest.

🕰️ Sleep Pressure and Circadian Rhythm Development

As babies grow, two biological forces begin to shape sleep patterns:

• Sleep pressure builds the longer a baby is awake, helping them fall asleep more easily when tired.

• Circadian rhythm (the body’s internal clock) starts forming around 3–4 months, influenced by light exposure, caregiving routines, and feeding patterns.

Together, these systems gradually organize sleep so babies begin to have longer night stretches and more predictable naps — though this development takes months to mature fully.

💤 The Four-Month Transition

Around 4 months, babies begin sleeping in cycles more like adults, shifting between light and deep sleep. Parents often notice more frequent night waking or shorter naps — a normal adjustment as the brain reorganizes sleep architecture. Supporting your baby through this period with responsive care, contact, and consistent routines helps them adapt without unnecessary stress.

🌼 Consolidating Sleep and Naps

By 6–8 months, daytime sleep often consolidates into 2–3 naps, with nighttime stretches becoming longer. By 10–12 months, most babies nap twice daily and may sleep 10–12 hours overnight — though variation is wide. Some babies are “larks”, tiring early and waking early, while others are “owls”, preferring later bedtimes and wakeups.

⚡ When Sleep Suddenly Changes

A sudden shift in sleep can signal many things:

• 🌱 Developmental leaps (new motor or cognitive skills)

• 🦷 Teething or illness

• 👀 Increased distraction leading to missed feeds

• 🍽️ Growth spurts requiring more calories

If your baby suddenly sleeps much longer, you may need to pump or hand-express to protect your milk supply until your body adjusts. If sleep shortens and fussiness increases, check for illness or feeding adequacy before assuming it’s “just regression.”

🌤️ Supporting Rest and Regulation

• 🕯️ Keep the environment calm and predictable — dim lights, reduce noise, and use gentle transitions.

• 👶 Watch for sleep pressure cues: zoning out, rubbing eyes, turning away, or fussing. Act quickly when you see them.

• 💞 Respect your baby’s temperament — some babies need help winding down, while others drift off easily.

• 💧 Remember that crying before sleep isn’t always protest; sometimes it’s how babies release stimulation from their day.

📊 A Normal Range of Sleep in the First Year

Age	Average Total Sleep	Night Sleep	Naps
0–3 months	14–17 hours	8–9 hours	3–5 naps
4–6 months	13–16 hours	9–10 hours	3 naps
7–9 months	13–15 hours	10–11 hours	2–3 naps
10–12 months	12–15 hours	10–12 hours	2 naps

💗 A Gentle Reminder

Every baby’s sleep story is unique. Rather than chasing strict schedules, focus on connection, feeding on cue, and reading your baby’s signs of readiness and fatigue. Over time, your baby will learn to regulate their sleep with your calm, responsive support.

👩‍⚕️ Author

Andrea Herron, RN, MN, CPNP, IBCLCOwner, Growing With Baby – San Luis Obispo, CAwww.growingwithbabyslo.com

Andrea Herron is a pediatric nurse practitioner and International Board-Certified Lactation Consultant (IBCLC) specializing in infant feeding, sleep development, and responsive parenting. She teaches parents and professionals how babies communicate through their behavior, helping families nurture healthy sleep and feeding relationships without sleep training. Through her Growing With Baby practice, Andrea offers private consultations, professional training, and community support groups for new parents.