A sensed presence is the distinctive feeling that another conscious agent is present alongside one's own self.   This occurs despite a complete absence of clear sensory or perceptual evidence to justify the feeling. In terms of its general location, the consciousness can be perceived as either present in a nonspecific part of the external environment, within one's own head, or as embedded within a specific object, such as a tree or an inanimate object.
While its intentions are often felt to be unknown, it can also interpreted as some kind of a malicious predator or a loving guardian. This is seemingly dependent on the person's current emotional state and is often further elaborated upon by the feeling that the presence is following the person, spying on them, protecting them, or simply observing them.
Sensed presence often precedes and leads into hallucinatory effects, such as autonomous entities and autonomous voice communication. It is also often accompanied by other coinciding effects, such as paranoia and delusion. It is most commonly induced under the influence of moderate dosages of hallucinogenic compounds, such as psychedelics, dissociatives, and deliriants. However, it is also relatively normal to experience this state of mind outside of psychoactive substance usage and mental illness.  In fact, it is quite common during high pressure situations, sleep paralysis, after the death of a loved one, as a child, as a symptom of parkinson's disease,  and within dark environments of any sort.
- SherMer, M. (2010). The Sensed-Presence Effect. Scientific American, 302(4), 34. (8) | https://www.scientificamerican.com/article/the-sensed-presence-effect/
- The silent companions - Ben Alderson-Day considers explanations for ‘feelings of presence’. | https://thepsychologist.bps.org.uk/volume-29/april/silent-companions
- Barnby, J. M., & Bell, V. (2017). The Sensed Presence Questionnaire (SenPQ): initial psychometric validation of a measure of the “Sensed Presence” experience. PeerJ, 5, e3149. | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5372834/#:~:text=The%20experience%20of%20'sensed%20presence,prominent%20in%20certain%20psychiatric%20or
- Fénelon, G., Soulas, T., De Langavant, L. C., Trinkler, I., & Bachoud-Lévi, A. C. (2011). Feeling of presence in Parkinson's disease. Journal of Neurology, Neurosurgery & Psychiatry, 82(11), 1219-1224. | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5372834/#:~:text=The%20experience%20of%20'sensed%20presence,prominent%20in%20certain%20psychiatric%20or