Why do people who abuse opium or alcohol take long to achieve anesthesia?

People who abuse opium or alcohol may take longer to achieve anesthesia because their bodies have developed a tolerance to the effects of these substances. This means that they require higher doses of anesthesia to achieve the same level of sedation as someone who does not abuse these substances. Additionally, chronic substance abuse can affect the body's ability to metabolize and eliminate drugs, leading to a slower onset of anesthesia. Furthermore, individuals who abuse opium or alcohol may have underlying health issues or organ damage that can impact the effectiveness of anesthesia.