As a mother of 3 kids, I understand how you feel
Because of the sensory integration disorder or being too excited before going to bed, kid constantly changes sleeping positions, kicks the quilt and is very easy to catch a cold.
When the air-conditioner is on or when the weather cools down, you always check if he is well covered with a quilt before going to bed, avoid him from catching a cold. You always wake up and cover your child with the quilt many times at night. You will feel that good sleep is much better than the best cosmetics.
You may choose a sleeping bag, but children are very resistant to being tied up. As the child grows taller, you have to change the sleeping bag frequently which will cost you hundreds of dollars. It is also difficult to find a suitable sleeping bag for a kid over 6 years old.