My sister inlaw son (4yr) just swallow a r1. are there anything we need to be scared or alert of. he says he feels tired and want to sleep?

Can call his doctor: A coin in the stomach is less worrisome because it should come out the butt. A question in that case is, "What other objects has he swallowed?" If a coin is stuck in the throat or esophagus, then the doctors in the ER can make a plan to remove it or get it into the stomach. It's best to talk with his doctor or go to the ER. Websites say the R1 is ~19mm diameter, which is big enough to worry some.