Is there any way that you can tell whether you are awake or sleeping ?

1. Is there any way that you can tell whether you are awake or sleeping ? Is Descartes right that he cannot tell the difference ? Try to identify and explained at least two ways of that dreaming experiences and waking experiences are different2. Why does Berkeley day the existence of material objects. Explain his view of subjective idealism. Do you accept or reject his theory? Why or why not ?