Scientists have asked a question about the human brain: How does it restart after sedation, coma or deep sleep?

Using a group of 30 healthy adults who were sedated for three hours, a study revealed some ideas about how the brain can pull itself back into consciousness.

And it turns out that the brain switches back one section at a time, rather than turning it on all at once — and abstract problem-solving abilities, as dealt with by the prefrontal cortex, are the functions that come back to work faster. Other areas of the brain, including those that manage reaction time and attention, take longer.

Anesthesiologist Max Kells, from the University of Pennsylvania, said: ‘Although surprising at first, it makes sense from an evolutionary point of view that higher cognition needs to recover early. For example, if someone is waking up to a threat, structures such as the prefrontal cortex The front will be important to classify the situation and develop a plan of action.”

A variety of methods were used to measure what was going on in the brain, including electroencephalogram (EEG) scans and cognitive tests before and after the scan. These tests measured reaction speed, memory retrieval, and other skills.

When analyzing the EEG readings, the researchers noted that the frontal areas of the brain – where functions including problem-solving, memory and motor control are located – became particularly active as the brain began to recover.

The comparison with the control group showed that it took about three hours for those who underwent anesthesia to fully recover.

The team also followed up with the group participants about their sleep schedules in the days following the experiment. The experience did not appear to negatively affect the sleep patterns of those who underwent anaesthesia.

Anesthesiologist Michael Avidan of the University of Washington said: “This suggests that the healthy human brain is malleable, even with prolonged exposure to deep anaesthesia. Clinically, this suggests that some cognitive disturbances that we often see for days or even weeks during recovery from anesthesia and surgery – such as Delirium – may be attributable to factors other than the persistent effects of anesthetics on the brain.”

And not many surgical procedures would be possible without anesthesia, which is an effective and controlled way to shut down consciousness in the brain – something that can happen involuntarily in a coma.

Despite their widespread use, we don’t really understand how anesthetics work in fine detail, even if we figure out how to use them safely. There are plenty of ideas about how the brain handles these drugs, but no concrete evidence yet.

The latest findings could not only help with treatments and patient care – after major operations involving anesthesia, for example – but also give scientists a better understanding of the brain and how it responds to the disorder.