Sleep Vs Coma

www.frontiersin.org encountered in the vegetative state makes it utterly difficult to identify possible REM sleep other than by the presence of muscular atonia and eye movements – note that nocturnal penile erections have been convincingly shown in vegetative patients (Cologan et al., in press). The brain’s metabolic activity in a coma, as measured by fluorodeoxyglucose positron emission tomography or FDG-PET, decreases to about half of normal waking values, and to ~40-50% of normal values in the vegetative state. These massive decreases in troencephalography (EEG) shows similarities between coma (or the vegetative state) – classically showing diffuse slowing of the brain’s basic rhythms – and deep (stage 3-4) sleep. EEG spindle activity (the hallmark of stage 2 sleep) can also be observed in some comatose or vegetative patients and seems to be a predictor of good outcome. Whereas coma patients will never show the EEG characteristics of REM sleep, it remains controversial whether vegetative patients may present periods of REM sleep. The very unstructured and slow waking EEG What are the differences between coma and sleep? Can patients in coma and related states have self-awareness or dreamlike experiences as can be encountered in sleep? Behaviorally, a coma may resemble deep sleep – the major difference being that comatose patients will never open the eyes, not even when intense or noxious stimuli are applied. Patients evolving from a coma to a vegetative state may, in turn, be compared to sleepwalkers – only showing reflex or automatic behavior, but not command following (Laureys, 2005). In addition, elecSLEEP VS COMA