What should baby wear to sleep?
keep it cool
It’s important that baby isn’t overdressed and his or her room is cool because if it’s too hot, the likelihood of SIDS can increase. Your baby’s sleep space should be between 68 and 72 degrees Fahrenheit.
Newborn baby
A newborn should be dressed in a onesie or cotton pajamas with a swaddle. During warmer months, a short-sleeve onesie is enough; as it gets colder, swap for long-sleeves and add pants. Unless it is extremely cold, avoid fleece or other heavy fabrics.
infant
As baby starts to roll and you stop using a swaddle, you can add a sleep sack for an extra layer. Underneath the sleep sack, you can have a short-sleeve or long-sleeve onesie. If it is colder, your baby can wear pajamas. Again, unless it’s really cold, avoid heavy fabrics, and choose a fleece sleep sack.
infant / toddler
There isn’t a “right” time to stop using a sleep sack. Most sleep experts suggest before the your baby is a year, but some toddlers use sleep sacks until they’re much older. When you decide to stop using one, your baby can sleep in pajamas. For the warmer months, choose cotton and short-sleeve or shorts. In the colder months, you can use fleece or footed-pajamas.
naps
What should you do for naps? That depends on your baby! Using swaddles or sleep sacks can be a great way to signal to your baby that it’s time to sleep. But, if your baby naps well without it, you can use it only as a signal for bedtime.