No, 9 months is not too old for a sleep sack. Sleep sacks can be used for babies and toddlers up to 24 months or even beyond, depending on the child's size and comfort level. They can be a safe alternative to loose blankets, especially for babies who are active sleepers and may kick off blankets during the night. When selecting a sleep sack, ensure it fits well and allows enough room for movement.
Long sleeve sleep sacks can be a good option for cooler temperatures or if your baby tends to get chilly during sleep. They provide added warmth and comfort without the need for extra blankets, reducing the risk of suffocation. However, in warmer climates or if your child tends to sleep hot, short sleeve or sleeveless sleep sacks might be more suitable. Always choose a sleep sack made from breathable fabrics like cotton.
Using a long sleeve sack or layering with a bodysuit can add arm warmth if needed.A baby's arms are often exposed in a regular sleep sack, but this does not necessarily mean they will get cold. Babies do not rely on their arms for heat retention and temperature regulation to the extent that their core does. As long as baby's torso, back, and legs stay warm in the sack, their arms being out is not a significant concern.