After induction of general anesthesia, maintaining the patient unconscious throughout the entire duration of the procedure is achieved by continuous administration of anesthetics. The depth of anesthesia should be continuously assessed and the dosage of anesthetics adjusted based on surgical stimulation and patient’s features. Common reactions to surgical stimulation denoting insufficient depth of anesthesia include somatic responses such as movement, coughing, and changes of respiratory pattern or autonomic responses such as tachycardia, hypertension, mydriasis, sweating, or tearing. Patients with history of alcohol use disorder or on long-term use of sedatives and/or opioids may require larger doses of general anesthetic. Failure in providing adequate depth of anesthesia may result in intraoperative awareness, which occurs in 0.1% to 0.2% of general anesthetics and is more frequent in certain high-risk surgical populations (eg, trauma, cardiac surgery, and obstetrics). Factors that increase the risk of awareness include the use of muscle relaxants and anesthesia techniques such as nitrous oxide combined with opioid medications without other hypnotic agents. Intraoperative monitoring of the cortical electroencephalogram (eg, SedLine monitor or BIS) and auditory-evoked potentials may be useful for monitoring depth of anesthesia, especially for total IV anesthetics, but their utility is controversial when used with volatile anesthetics.