My son is 5 months old. he would sleep through the night but now hes waking up for more milk. should i start feeding him cereal?

Start cereal: Your baby is growing well and needs more food ,Thiis is the right time to start cereals .To start with give once a day ,may be in evening in addition to his regular milk intake .after a week or so give cereal twice a day .He will sleep through the night well .

Bottle-fed babies: can be weaned a 1 year to a maximum of 16-21 oz. milk & milk products/day. Offer milk in open-mouth cups with meals only. Let him self- feed with his hands & a spoon & at 3 meals & 2 snacks/day. He needs a Dr. visit, a check for anemia & a dental visit. At a set bedtime, read, brush his teeth & put him in his crib drowsy, but awake to learn to self-calm to sleep. Crying 1st ^es, then stops.

Yes, you can start: feeding him cereal (during the daytime).It probably will not help him sleep at first, but as you advance his solids,he will most likely go back to sleeping longer at night.I would try not to give him an extra bottle at night.It will be hard to break him of that habit. A good resource is: https://www.healthychildren.org/English/ages-stages/baby/feeding-nutrition/Pages/Switching-To-Solid-Foods.aspx