Why Sleeping bags/suits?
For newborn babies, it is most recommended to swaddle them for a secured, womb-like feeling. As children grow bigger, they will demand more freedom to move their arms and legs, and that's when sleeping bags are needed. Compared to blankets, sleeping bags are warmer and safer, and they save you from getting up to check if your little one has escaped from the blanket during the night.
When your children can independently roll over, it is worth considering dressing them in a sleeping suit with legs, so that they can move and adjust positions by themselves more easily in the cot. It can be dangerous if the baby rolls over to face down but then has difficulty rolling back when the sleeping bags do not provide enough room to move their legs. It is also easier to train your child to form a nice bed routine, since he or she can walk freely in a sleeping suit and engage in multiple bedtime activities, such as brushing teeth and picking a book to read.