What milestones should a 4-month-old have?

Most 4-month-olds hold their head steady without support, may roll from tummy to back, bring their hands to their mouth intentionally, reach for objects, laugh aloud, and babble with varied sounds.

What is the 4-month sleep regression?

The 4-month sleep regression is a permanent change in how a baby's sleep cycles mature. Babies begin cycling through light and deep sleep like adults, which causes more night wakings. It typically lasts 2–6 weeks.

When do babies start rolling over?

Many babies roll from tummy to back first, often between 3 and 5 months. Rolling both ways usually comes between 4 and 6 months. Each baby is different — a month's variation is common.

When do babies first laugh?

Most babies laugh for the first time between 3 and 4 months. Laughter is usually triggered by social games — peek-a-boo, raspberries, or silly voices — and is a key social milestone.

Guides · Development

4-month baby development: rolling, laughing & the sleep regression

Four months is a landmark age. Your baby's personality is becoming unmistakable — they laugh, engage, and show preferences. Physically, they're stronger and more coordinated. This guide covers what most 4-month-olds can do, what the 4-month sleep regression means, and how to support your baby through this busy month.

Motor development at 4 months

Head control: by 4 months, most babies hold their head steady and upright without support. When held in a sitting position (with support), the head doesn't lag behind.

Rolling: rolling tummy-to-back often happens first, sometimes accidentally during tummy time. By 4 months many babies can do this consistently. Rolling back-to-tummy tends to come slightly later.

Brings hands to mouth: reaching the hands to the mouth is now intentional. Babies use this to self-soothe and to explore objects.

Reaching for objects: babies begin to reach (and sometimes grab) objects placed in front of them. The reach isn't accurate yet, but the intention is there.

Supported sitting: with support at the hips, many 4-month-olds can sit briefly. The back isn't strong enough for unsupported sitting yet.

Weight bearing on legs: when held upright with feet touching a surface, babies often push down — an early precursor to standing.

Cognitive development at 4 months

Interest in mirror: babies become fascinated by their own reflection. They don't recognize themselves, but a mirror provides rich visual and social stimulation.

Recognizing bottle or breast: by 4 months, many babies show excitement when they see the bottle or chest positioned for feeding — they anticipate what's coming.

Object tracking: improved eye control means babies can track a moving object smoothly across their full field of vision.

Cause and effect: babies begin to understand that their actions have effects — shaking a rattle produces sound, crying brings a caregiver.

Attention span: while still short, attention spans are longer than at 2 months. Babies may engage with a toy or your face for 30–60 seconds.

Social and emotional development at 4 months

Laughter: the first laughs are one of the most memorable moments of parenthood. Most babies start laughing between 3 and 4 months, in response to tickles, funny sounds, or social games like peek-a-boo.

Shows excitement: anticipatory excitement — wiggling arms and legs when a familiar person approaches — is common at 4 months.

Preference for people: babies increasingly prefer familiar caregivers over strangers and may need time to warm up to new faces.

Initiating social games: some 4-month-olds will attempt to initiate interaction — making sounds and waiting for your response.

Language and communication at 4 months

Babbling: the cooing of earlier months gives way to more varied sounds. Babies string together consonant-vowel combinations and experiment with different pitches.

Blowing raspberries: a favourite at this age. It's mouth exploration and early articulation practice.

Turn-taking: babies get better at taking turns in "conversation" — making a sound, pausing, and waiting for your response.

Responding to name: some babies begin to turn toward their name around 4–5 months, though this becomes more reliable around 6–9 months.

The 4-month sleep regression

The 4-month sleep regression is not a temporary setback — it's a permanent, normal change in how sleep is structured. Before 4 months, babies cycle quickly between active and quiet sleep. Around 4 months, the sleep architecture matures and begins to resemble adult sleep cycles, with distinct light and deep phases. When babies pass through the light phase, they may fully wake, and if they relied on feeding or rocking to fall asleep initially, they'll need the same to fall back asleep.

Signs include: suddenly waking more frequently at night, shorter naps, increased fussiness, difficulty settling.

What helps: maintaining a consistent bedtime routine, responding calmly to night wakings, offering feeds as needed, and knowing it usually improves within 2–6 weeks.

Red flags to discuss with your pediatrician

Doesn't hold head steady by 4 months
No laughter or social smiling
Doesn't reach for objects
Shows no interest in faces or voices
Seems stiff or unusually floppy

Raise any concerns at the 4-month check-up.

How Bebblo helps at 4 months

The 4-month sleep regression means night wakings can become unpredictable again. Logging feeds and sleep in Bebblo helps you see patterns in the chaos — when the last feed was, how long sleep stretches lasted, whether daytime naps are affecting night sleep. This data is useful for your own sanity and for your pediatrician.

This article is for general guidance and does not replace your doctor's advice. The 4-month sleep regression is normal, but if you have concerns about your baby's sleep or development, talk to your pediatrician.

Track sleep and feeds with Bebblo

Bebblo logs every feed, sleep, and nappy in seconds — especially useful during the 4-month regression. Free, works offline, no account needed.