My 20-month-old wakes from a nap in a very bad mood. He is inconsolable even if you give him everything he wants. The moment he gets it, he doesn't want it; then he throws it or pushes it away. As his anger progresses he wants to hurt whoever is holding him. He does this by pulling hair or grabbing and twisting clothing or jewelry. We have resorted to time-outs when trying to console does not work and he tries to hurt us. For the time-out, he is put in a child-safe bedroom alone with the door shut. Of course we are right outside the door waiting. As soon as there is a break in the screaming, we open the door and ask if he is all done. He usually screams "no" and tries to re-shut the door himself. This happens three or four times until he can be coaxed to come out and have fun with us. Sometimes, but not always, if he is fed immediately upon waking his mood changes and we avoid all the upset. But we can never tell if that will work or we will be wearing the food. Are we handling this in the right manner or is there a better way? How long can we expect this behavior to continue?
If he is otherwise a happy, loving child, the answer may be a simple one. You even give a clue in your question.
Some children have a low blood sugar when they awaken because it has been hours since they ate and they are not awake to demand food when they get hungry. Once they are in a full-blown tantrum, feeding may not work well because it is too late; they are out of control. This can occur either in the morning or after a nap.
Another possibility is that your toddler may not be fully awake after his nap. His feelings of disorientation may be triggering the behavior you describe.
Try giving him a snack shortly before putting him down, preferably one with some complex carbohydrates such as crackers or bread and a simple sugar such as juice. This may stave off his hunger at awakening and you may get back the sweet child you usually enjoy. If this doesn't do the trick, continue the time-out approach you've been using. This may help your child calm down and orient himself.