It is normally assumed that those near death are so physically compromised that they are generally unconscious. However, 17% of those who nearly died reported that they experienced near-death experiences (NDEs), such as out-of-body experience, heightened senses, encountering a mystical light with a flush of positive emotion.

AWARE-II was a multi-centred study that evaluated the consciousness and awareness of patients in cardiac arrest (CA) during cardiopulmonary resuscitation (CPR). In the study, 567 patients were included, of whom only 28 were interviewed after being revived from CA due to the low survival rate. Of the 28 patients, 39% had memories or perceptions during the CPR, 21% recalled an NDE, 7% had memory emergence during CPR, 7% had memory emergence post-CPR, and 11% had a dream-like experience.

The researchers also investigated how the brain regional oxygen saturation (rSO2) and electroencephalogram (EEG) were related to the consciousness of the patients. Among 28 interviewed survivors, the mean rSO2 was similar between those with and without memories (53.45 ± 2.72 vs. 46.70 ± 18.25, p = 0.55). Regarding the EEG activity, although the absence of cortical brain activity was dominant (47%), near-normal/physiological EEG with delta and theta activity were recorded in 22% and 12% of scans respectively (up to CPR 60 minutes), alpha wave was recorded in 6% of data/images (up to CPR 35 minutes), meaning that some patients experience clinically undetectable consciousness. The near-normal-physiological EEG activity that emerged between 35 and 60 minutes into CPR suggested the possible resumption of cognitive and neuronal activity and may imply the possibility of utilising it as a biomarker for measuring consciousness. The researchers believe NDEs and consciousness during CA are yet to be elucidated.

References: 

Long J. Mo Med. 2014;111(5):372-380. 

Parnia S, et al. Resuscitation. 2023;191:109903