Can you be aware of nothing? The rare sleep experience scientists are trying to understand

For some people, sleep brings a peculiar kind of wakefulness. Not a dream, but a quiet awareness with no content. This lesser-known state of consciousness may hold clues to one of science’s biggest mysteries: what it means to be conscious.

- BY ADRIANA ALCARAZ-SANCHEZ Postdoctoral Fellow in Philosophy of Mind and Cognitive Science, University of Edinburgh

The state of conscious sleep has been widely described for centuries by different Eastern contemplative traditions. For instance, the Indian philosophical school of the Advaita Vedanta, grounded in the interpretation of the Vedas one of the oldest texts in Hinduism - understands deep sleep or “sushupti” as a state of “just awareness” in which we merely remain conscious.

Similar interpretations of deep sleep are made by the Dzogchen lineage in Indo-Tibetan Buddhism. According to their teachings, different meditative practices can be followed during wakefulness and sleep to acknowledge the “essence” of consciousness. One of those meditative practices is that of dream yoga or luminosity yoga, which enables the practitioner to recognise the states of dream and sleep. This aims to bring them to a state of “pure awareness”, a state of being awake inside sleep without thoughts, images or even a sense of self.

For western science, this state poses a conundrum. How can you be aware without being aware of something? If these reports are accurate, they challenge mainstream theories that treat consciousness as always about an object. For example, my awareness of the laptop in front of me, or the blue sky rising above my window, or my own breathing. The existence of this state pushes us to reconsider what consciousness is.

Objectless sleep experiences

My colleagues and I set out to explore what a content-free state during sleep feels like in a series of studies. We first surveyed 573 people online about unusual forms of sleep experiences, including forms of sleep consciousness that might be simpler or more minimal. For example, an awareness following the dissolution of a dream, or a bare awareness of the fact that you are sound asleep.