Tag Archives: delta waves

Doctors record brain activity in a deceased patient 10 minutes after death

A medical oddity was recently recorded by doctors who studied the electroencephalography (EEG) diagrams from four terminally ill patients right at the moment life support was unplugged. One of the patients had brain activity even ten minutes after the heart stopped which is totally not normal to say the least. Nobody knows for sure what happened.


When a person dies, 99% of the time this will be a ‘cardiac death’ meaning death has occurred when the heart stopped beating. Without the heart pumping blood, vital oxygen doesn’t reach the brain resulting in death. Once the heart stops beating, it shouldn’t take long before death sets in because cells in the brain start shutting down. In fact, it can happen even sooner, as we’ll notice later.

According to a 2013 study that recorded death-related brain activity in rodents, there are four distinct stages of brain death. Stage 1 is cardiac arrest and it takes only approximately 4 seconds between the last regular heartbeat and the loss of oxygenated blood pulse. The second stage lasts about 6 seconds and ends with a burst of low-frequency brain waves, the so-called ‘delta blip’ or ‘death wave’. In the third and final active death stage there is still some brain activity which lasts around 20 seconds which, very intriguingly, resemble brain waves recorded in waking state leading some to speculate this may be the source of “highly lucid and realer-than-real mental experiences reported by near-death survivors”. Stage four: dead for good.

Studying a person’s final brain activity is very challenging, though, for obvious reasons. There is still much we don’t know about what goes on inside the brain once a person passes but this strange recent case reported by Canadian researchers is just mind-boggling.

Patient #2, for instance, out of the four investigated by Loretta Norton and colleagues of the University of Western Ontario, Canada, ceased displaying EEG activity 10 minutes before the heart stopped beating. Patient #4, however, displayed the opposite pattern. All four EEGs are shown in the diagram below where ‘time 0’ represents the moment of cardiac death and yellow vertical lines show brain activity.

The yellow lines you’re seeing are the delta wave bursts, which are the same brain waves we experience during deep sleep. As you can notice, each of the four EEGs exhibits a unique pattern. This may mean that, in some way at least, no two deaths are the same.

“Electrocerebral inactivity preceded the cessation of the cardiac rhythm and ABP in three patients. In one patient, single delta wave bursts persisted following the cessation of both the cardiac rhythm and ABP. There was a significant difference in EEG amplitude between the 30-minute period before and the 5-minute period following ABP cessation for the group, but we did not observe any well-defined EEG states following the early cardiac arrest period,” the researchers wrote in their paper published in The Canadian Journal of Neurological Sciences.

The real star of the paper is this patient #4. The researchers have no biological explanation for what may have prolonged brain activity for this much time. All four patients were terminally ill and were on a tonne of medication before life support was unplugged. The sample size of the study which includes only four recorded deaths also makes difficult to draw any conclusions. Again, there are only a few dozen people who have had their brain activity recorded mere moments before death. Bearing this in mind, the researchers think that this anomalous delta wave pattern could be due to some faulty equipment.

That may sound disappointing to hear but the truth is no seems to know what happened here.  In 2011, the same ‘death waves’ were recorded in a rodent even one minute after it was decapitated yet again highlighting the difficulty of pinpointing the moment of death. But the good news is that we’re constantly learning more. Maybe one day, science will become so advanced it will unravel what happens even in death. What that happen, we might be even able to trick it.