Consciousness as we know it is not continuous or homogeneous. Our given consciousness is intermittent and variable. There are degrees of consciousness.
Without going into a detailed definition of "consciousness" here, I will try to illustrate my point with a few simple examples.
Consider the difference between dreaming and being awake. What distinguishes a dream from waking life? One of the distinguishing characteristics of a dream is the lack of self-consciousness, specifically the lack of a sense of being present. While you’re dreaming, you aren’t aware that you’re dreaming. While you’re dreaming you have little sense of self, little consciousness. You are merely "aware" of the content of the dream. Awareness is a register of impressions, not specifically a sense of being present.
When you are awake, you can become aware of being awake. You can become self-conscious while awake. While you are awake you can have a sense of being present, although perhaps only for a brief moment.
In as much as consciousness is a sense of being present, we are unconscious during a dream. In other words, we are aware and unconscious. Or, to put it another way, we are less conscious. If we regard awareness itself as a form of consciousness, then while we are dreaming we are less conscious than we are while awake.
Consider the difference between your state of consciousness when you’re tired and your state of consciousness when you’re vitalized. When you’re tired, you are less conscious. You are less self-aware. Your sense of being present is dim compared to when you are vitalized. When you have a lot of vitality, you are more conscious. Your sense of being present becomes strong. Consciousness tends to diminish with diminishing vitality. When you lie in bed at night to go to sleep, your sense of being present diminishes by degrees. You lose consciousness as you drift into sleep.
All of this is rather common sense. It’s a stepping stone to a deeper understanding of what consciousness is, the significance of consciousness. There is a potential latent within our elementary consciousness. Pay attention and discover that potential.