My wife and I are in a similar season of life and had great success using the Ferber method for sleep training our little boy. He now barely fusses when we put him down to sleep at night and goes to sleep very quickly, although it still takes him some time to agree to go down for a nap. If you do want to use some herbs, I would make a chamomile tea and dilute it with some water about half an hour to an hour before sleep to help your little guy calm down.