Babies can safely wear just a bodysuit for sleep when some guidelines are followed. Choose a snug fitting, lightweight cotton bodysuit to prevent loose fabric bunching. Ensure the bodysuit fully snaps up around the diaper area. Watch that it does not ride up on the waist or legs during sleep. Without the risk of blankets, bodysuits allow arm and leg movement for development. They contain the torso for warmth. For hot rooms, a diaper with bodysuit alone suffices.

It is generally safe for babies to sleep in Sleeveless bodysuits, pajamas, or other garments when the temperature is warm. Sleeveless allow airflow to prevent overheating which is a SIDS risk. Choose lightweight, breathable fabrics like cotton or bamboo. Combine with lightweight sleep sacks if needed. Watch for signs of being too chilled like red skin on arms or goosebumps. For cooler temps, transition to long sleeves layered under sack.

In colder weather, you can consider using a bodysuit as an extra layer for added warmth.
Bodysuits are particularly useful when dressing babies in outfits that might ride up or become untucked, as they help keep everything in place. They're also practical for keeping diapers in place and preventing them from peeking out.