Note how in our dreams we always dream as we are today e.g. for me today I will dream as I am a 52 year old, I don’t dream from the perspective of a 10 year old as in the past tense or in the future tense as a 70 year old. So if all your dreams are present tense just like your waking state isn’t it possible that all that’s real is the present. Advaita Vedanta holds that the dream and waking states are states of consciousness. This needs to be distinguished from past memory and future imagination. All that is true is the present moment.