How Does Anaesthesia Make You Unconscious?

Despite over 175 years of use, the exact mechanism of general anaesthesia is not fully understood. Most inhaled anaesthetics (like sevoflurane) and intravenous agents (like propofol) enhance inhibitory neurotransmission — primarily by potentiating GABA-A receptors, which increase chloride flow into neurons and dampen brain activity. This disrupts the thalamocortical communication needed for conscious awareness. Different brain regions are affected sequentially: the cortex (awareness) first, then subcortical areas (memory and motor control). An anaesthesiologist continuously monitors depth of anaesthesia using EEG-derived indices, adjusting drug doses in real time to keep the patient safely unconscious throughout surgery.