04/17/2026
Most parents think their baby is dreaming when they smile in their sleep… but that’s not the whole story.
Newborn smiles during sleep are usually reflex smiles, not emotional ones. Their brain is still developing, and these little grins happen during active (REM) sleep when their nervous system is firing and wiring.
It’s actually a good sign — it means their brain is growing and making connections.
Real, social smiles? Those start showing up around 6–8 weeks when your baby locks eyes with you and smiles on purpose. That’s when it gets really fun.
So yes… it’s adorable. But it’s also biology doing its job.