If you are experiencing difficulty with recognition of "Wake up", avoid running the words together and insert a micro pause between each word. However don't pause too much between each word — although Dragon needs to hear each word separately, it needs to hear the phrase as a unit, without a long pause between each word.
As an alternative, you could try "Listen to me". If you stress the word 'to', this tends to force pronunciation of each word separately, rather than running the words together.
These phrases are often misrecognised by Dragon if the words are run together.