In this fifty second verse and dharana of the Vigyana Bhairava Tantra, Shiva says:
In the twilight before sleep
Senses no longer reaching out
Let Devi shine
As we doze of to sleep, we move into a sub conscious zone, which lies between the conscious awake state and the unconscious sleep state. This is the state of dreams. In medical terms this is also called the rapid eye movement or REM sleep zone. In this zone, the brain wave patterns are in the alpha mode, between 8 and 12 Hz, as against the beta mode in the waking zone for adults between 13 to 20 Hz. This is the twilight zone between the awake state and the deep sleep state.
The Mandukya Upanishad explains 4 states of consciousness that the human mind body moves between. The first is that awake state, in which we consider ourselves to be aware of what we’re doing. Shankara disputes this with his concept of maya, saying that what we are aware of in this state is not the true reality but merely the perception of what we see of the outside world through our conditioning. In modern psychological neuro linguistic programming terms we call this mind maps.
The second state of the body mind is the dream state. In the first state of being awake, we are conscious of our physical identity and are in our gross mind body state. In the second state of dream, we’re no longer conscious of our physical mind body identity, and are in the subtle mind body state. This is why, for instance, if we dream of being a attacked say by an animal we wake up from a nightmare unscathed. The dream seems very real but does not affect us physically.
The third state of the body mind is the deep sleep state. This is the causal state, in which either there are no thoughts that we are aware of or the thoughts are in a seed form if we bring awareness into the state. This is the state in which we can actually reframe our thoughts and recreate our future, if we’re in awareness in the state. This is called the state of prajna, which means awareness. Yoga Nidra meditation allows us to access this state in awareness.
The last state of consciousness of the human mind body, called simply the Fourth state or turiya in Sanskrit, is one in which one disengages from thoughts merely being a witness to them. This is the state all spiritual seekers aspire to.
In this verse Shiva talks about the twilight zone which may either be between the awake and the dream states, or in the dream state itself. What is more relevant here is the distancing from sensory perceptions and thoughts. In this twilight zone between wakeful and dream states, if one is able to merely witness what is going on in our minds, without being attached to the thoughts, we reach the state of the divine.