What Is a Co-Sleeper for Baby? | Bedside Sleep Basics

When you search “what is a co-sleeper for baby,” you’re usually looking at a bedside bassinet, a portable crib, or a similar product designed to sit right next to an adult bed. The term is sometimes used loosely, so it’s worth knowing the difference between co-sleeping with a product and bed-sharing. The American Academy of Pediatrics (AAP) recommends room-sharing — your baby sleeps in your room, near your bed, but on their own dedicated infant surface — for at least the first six months.

This article lays out what a co-sleeper is, what it isn’t, and the safety rules that matter for your baby.

What “Co-Sleeper” Means in Practice

In the U.S., a co-sleeper generally means a bedside sleeper or bedside bassinet that attaches to or sits flush against your bed. The idea is simple: your baby is within arm’s reach for feeding, soothing, and checking on, but the baby is still on a flat, firm surface made for infants — not in your bed.

The AAP’s evidence review defines cosleeping broadly as a parent and infant sleeping in close proximity, so they can see, hear, or touch each other. That can mean the same surface or different surfaces. But the guidance from the AAP is clear: room-sharing on a separate surface is what’s recommended, and bed-sharing is discouraged. The AAP’s Safe Sleep recommendations specifically state that infants should sleep in the parents’ room on a separate surface designed for infants, close to the bed.

What a Co-Sleeper Is Not

This is where confusion creeps in. Some parents use “co-sleeper” to mean sharing the bed, but that’s not the same thing. A co-sleeper product is a separate infant sleep surface. Bed-sharing — bringing the baby into the adult bed — is not recommended by the AAP. The increased risk of injury or death from bed-sharing is well documented, and no bedside attachment turns an adult bed into a safe infant sleep surface.

You should also never use a co-sleeper as an in-bed sleep solution. If you’re exhausted, have had alcohol or sedating medication, or your baby was born premature or with low birthweight, bed-sharing risks are even higher. And the AAP is emphatic about one thing: never sleep with a baby on a sofa, armchair, or recliner. Those cushioned surfaces carry extremely high risk, according to the AAP.

The Safe Sleep Rules That Apply to Any Co-Sleeper

Whichever bedside product you use, the safe sleep basics stay the same. These rules come straight from the AAP and the NHS safer sleep guidance, and they apply every single time.

• Always place the baby on their back to sleep.
• Use a flat, firm, noninclined surface — no wedges, no positioners, no padded inserts.
• Keep the sleep space free of pillows, loose blankets, stuffed toys, and bumpers.
• Put the baby in your room, close to your bed, but on their own separate surface.

That last point matters more than many parents realize. A bedside co-sleeper gives you closeness without the risks of sharing a mattress. If you’re comparing products, remember that official guidance is about an infant-designed separate surface — not just any attachment or bedside accessory.

Room-Sharing Vs. Bed-Sharing: What the AAP Recommends

The AAP is explicit about this in its Safe Sleep recommendations: room-share for at least the first six months, ideally longer. That means your baby sleeps in your room, near your bed, on a separate surface made for infants. Bed-sharing, in the AAP’s evidence review, is associated with increased risk of suffocation and other sleep-related deaths.

Here’s a quick comparison of the two arrangements so the difference is unmistakable:

The bottom line: a co-sleeper is a tool for safer room-sharing, not a workaround for bed-sharing. The AAP’s evidence base for the 2022 recommendations walks through these risks in detail, and the NHS safer sleep advice reinforces the same guidance on firm surfaces and back sleeping. When you’re ready to pick one, our roundup of the best co-sleepers for bed can help you compare models that meet these safety standards.