Study probes 'objectless sleep' and the Hindu concept of sushupti

Researchers at the University of Edinburgh are examining a rare sleep state in which people stay aware while sleeping but report no dreams, thoughts or sense of self. The phenomenon has drawn comparisons to the Hindu concept of sushupti, one of the four states of consciousness described in ancient philosophy as deep, dreamless sleep in which ego and the external world fade away, leaving a pure sense of existence. While sushupti is often discussed in spiritual or philosophical terms, scientists are now seeking empirical clues about what such an experience reveals about the nature of consciousness.

In the study, researchers began by surveying a broad online community, receiving 573 responses about unusual forms of sleep experiences. They followed up with in-depth interviews of 18 participants who said they had experienced an “objectless” form of sleep, in which awareness persisted but there was no accompanying sensory content, thoughts or sense of self. Several described a quiet, hazy presence or a feeling of nothingness — a void in which awareness alone remained. Adriana Alcaraz-Sanchez, the study’s lead author, told The Conversation that many participants connected the experience to contemplative traditions, while others described it without any knowledge of those practices.

During a second phase, the researchers pushed the envelope by teaching four volunteers a blend of meditation, visualization and lucid-dreaming techniques designed to help them stay aware as they drifted into sleep. Each participant signaled their awake state with a pre-agreed eye movement while an electroencephalogram tracked brain activity. The team found that objectless sleep experiences occurred at least intermittently during deep, non-REM sleep, suggesting a form of consciousness that defies conventional expectations about what the sleeping brain can know. “The existence of this state pushes us to reconsider what consciousness is,” Alcaraz-Sanchez wrote.

The findings appear to challenge the long-standing notion in Western science that consciousness depends on awareness of an object — whether that object is a coffee cup, a color, a breath or another content in the mind. In these rare sleep states, most of those objects disappear, leaving researchers to wonder whether awareness can persist in the absence of sensory content. Alcaraz-Sanchez noted that, historically, sleep consciousness has largely been explored through dreams or dream-like states; objectless sleep experiences hint at a broader, potentially content-free form of awareness.

The connection to sushupti in Hindu philosophy is not meant to equate a scientific finding with a religious experience, but rather to illuminate how different traditions have described periods of awareness without ordinary experience. Sushupti is often characterized as blissful sleep in which the ego dissolves and contact with the external world is suspended. In that tradition, the sleeper wakes rejuvenated, free from grief and worldly concerns. Scientists caution that while the parallel is intriguing, the modern study does not claim to prove a direct equivalence with sushupti; rather, it suggests that the mind may harbor higher levels of intrinsic awareness during sleep than previously thought.

The Edinburgh project follows a growing interest in consciousness research that looks beyond wakeful perception to what the brain can know when sensory content is minimal or absent. Some researchers have proposed that objectless sleep experiences may reveal a baseline form of awareness that does not rely on interacting with external objects or internal narratives. If confirmed, such findings could inform theories of consciousness, sleep architecture and even clinical approaches to sleep disorders, where disturbances in awareness during sleep can accompany conditions such as sleep paralysis or persistent intrusions of wakefulness into sleep.

Still, scientists acknowledge that the observations come from a small set of participants and a preliminary methodological framework. The initial online survey identified a larger pool of people reporting unusual sleep experiences, but only a subset could be described in depth, and the four volunteers in the experimental phase represent a first, exploratory step. Critics of the approach point out that self-reported experiences of awareness during sleep can be subjective and difficult to verify independently. The researchers themselves emphasize the need for replication with larger samples and more controlled experiments before firm conclusions can be drawn about the prevalence or significance of objectless sleep states.

If future work confirms that people can maintain a content-free form of consciousness during deep sleep, it would invite a broader debate about the locations and mechanisms of consciousness in the sleeping brain. It could also spur inquiries into how such states relate to meditation, lucid dreaming and other altered states of awareness. While the current findings do not overturn established sleep science, they invite scientists to consider a wider landscape of awareness that may operate even when the brain shows little to no external or internal content. As the researchers push forward, they aim to refine the methodology, broaden participant diversity and examine whether objectless sleep experiences have any lasting effects on cognition, memory consolidation or emotional processing after waking.

The study highlights a broader shift in sleep research: toward a more nuanced understanding of consciousness that does not hinge solely on dream content or explicit self-narratives. By exploring the boundaries between wakefulness and sleep, scientists hope to uncover the fundamental architecture of awareness itself. The work also underscores how ancient ideas about consciousness, such as sushupti, may gain new relevance as science probes the mind's most elusive states. The next phase of research will seek to determine how common objectless sleep experiences are across populations, what brain networks are involved, and whether deliberate practice can reliably induce and sustain awareness without sensory input during sleep. Only through rigorous replication and cross-disciplinary inquiry can researchers determine whether objectless sleep is a rare curiosity or a doorway to a deeper understanding of consciousness that bridges science and philosophy.

As scientists continue to untangle the threads of this phenomenon, the public conversation about sleep, consciousness and well-being may take a new turn. With more data, researchers hope to describe not just when people are dreaming or awake, but when they are truly aware—yet empty of sensory content—in the deepest reaches of sleep. If these findings hold, they could redefine what it means to be conscious and how the sleeping brain contributes to the mysteries of mind and self.

The study’s implications extend beyond theoretical debates. In clinical settings, a clearer map of sleep states could inform the diagnosis and treatment of sleep disorders, help researchers understand how memory consolidation operates in periods of minimal sensory input, and perhaps illuminate why some people report extraordinary clarity or well-being after awakening from deep sleep. For now, the notion that consciousness can exist without content during sleep remains a provocative finding backed by a small but intriguing body of evidence. As researchers plan further investigations, the scientific community will watch closely to see whether objectless sleep experiences become a durable landmark in the science of sleep and consciousness.