Near-death experiences (NDE) involve enhanced perception and memory, and have been linked to a surge in high-frequency brain oscillations. In anesthetized rats dying from an overdose of chloral hydrate, a surge in beta and gamma band power occurred in the hippocampus, with gamma power specifically tied to impending death. Theta band power was suppressed. Cardiac arrest only developed after breathing stopped and all oscillatory activity collapsed, showing that the high-frequency surge is not exclusive to cardiac arrest. The gamma synchronization in the CA1 region may contribute to NDEs that occur both with and without cardiac arrest.
Type 1 narcolepsy (NT1) involves the loss of hypocretin/orexin transmission, causing daytime sleepiness and abnormal mixing of REM sleep with wakefulness, leading to cataplexy, sleep paralysis, and dream-like hallucinations. Using deep learning of nocturnal sleep polysomnography signals (EEG, EMG, EOG), the study found that NT1 patients show abnormally short wake-to-REM transitions and mixing of wake, N1, and REM sleep stages. This mixing fluctuated across cortical locations, strongest in frontal and central regions, particularly the left hemisphere. The strongest discriminator was N1-REM mixing across central electrodes, with 4.3-fold higher dissociation in NT1 patients (Cohen’s d = 0.61). Local dissociations correlated with CSF orexin/hypocretin levels and MSLT severity. Hypnagogic hallucinations correlated with occipital dissociations, aligning with visual content. Orexin deficiency likely destabilizes REM sleep organization across cortical areas.