Expert AnswersDeborah Lin-Dyken, pediatric sleep disorders expert
You'll want to dress your baby in sleepwear that's safe and comfortable and that helps her maintain a good body temperature.
Contrary to what you might hear, baby sleepwear doesn't have to be flame resistant. Soft, breathable natural fabrics like cotton are fine, but they must be used in a garment that fits snugly to be safe. By U.S. law, as of June 2000, children's sleepwear must be labeled as either snug-fitting (so it won't easily catch fire) or flame resistant.
Avoid ribbons, strings, ties, and other decorative items that could get wrapped around your baby and pose a choking hazard.
As for how much to bundle up your baby, don't overdo it. Overheating is a risk factor for sudden infant death syndrome (SIDS).
Start by keeping the room at a temperature that's comfortable, not hot — 70 to 72 degrees is a good range. Then dress your baby for bed in whatever you're comfortable in plus one layer. So if you feel fine in one layer, put two layers on your baby.
Booties are a good way to keep her toes warm when it's chilly, and, since much of her body heat escapes from her head, a skull cap is also a good idea. Don't cover her up with big, fluffy blankets or comforters, though, because these could wind up over her head and lead to suffocation or SIDS. Opt for a sleep sack instead.
During warm weather your baby can sleep without extra layers. Just keep her away from direct air conditioning vents and drafty windows.
Editor's note: For more tips, see our expert's answer to "How can I keep my baby warm at night without blankets?"