For safety reasons, the American Academy of Pediatrics recommends babies sleep without any loose blankets, so at night it’s best to choose an outfit that keeps your baby comfortable without extra layers.
Avoid over-bundling your baby: most nights your infant can wear a onesie and a cotton swaddle, or cotton pajamas with feet. In the winter, heavier pajamas or an additional sleep sack (a sleeveless, wearable blanket) will work.
Older children tend to kick off their covers at night, so you may want to dress your toddler or young child in an outfit that works without blankets as well. Choose pajama fabrics that are breathable and won’t cause your child to sweat during the night. The same general principle of cool air for better sleep applies to children, so try to keep the room in the mid-60 degree range.