My baby is two months old and still not sleeping through the night. There's no proof that solid foods help your baby sleep through the night. What he really needs to sleep is a more fully-developed nervous system. Bottles with cereal added to them are not likely to help your baby sleep through the night either. And if cereal in a bottle is taking the place of your baby's breast milk or formula, he may be missing out on other important nutrients.
Most babies are ready for solid foods at about four to six months.
Your baby might be ready for solids if he can sit with support and can control his head. He no longer pushes food back out of his mouth, and he can move foods from the front of his mouth to the back with his tongue. And he probably seems interested in the foods he sees the rest of the family eating. Your baby's doctor will probably suggest an iron-fortified infant cereal as your baby's first food. After several days of doing well on rice cereal, you can try barley or oat cereal.