Patients commonly report that they have been dreaming when they awaken from general anaesthesia. Our hypothesis is that patients who report dreaming are less deeply anaesthetised during anaesthesia than patients who do not report dreaming. Depth of anaesthesia will be determined using a processed electroencephalographic monitor (called the BIS monitor).

In this study, we will record the depth of anaesthesia during surgery with the BIS monitor and then interview patients immediately upon emergence to determine whether they recall dreaming or not. The depth of anaesthesia of dreamers and non-dreamers will be assessed.

Inclusion Criteria:

• Age 18-50 years
• American Society of Anesthesiologists physical status 1-3
• Non-cardiac surgery under relaxant general anaesthesia
• Tracheal extubation planned at end of surgery

Exclusion Criteria:

• Inadequate English language skills (due to language barrier, cognitive deficit or intellectual disability)
• Major drug abuse or psychiatric condition
• Expected to be unable to co-operate or be available for followup

Patients presenting for elective non-cardiac surgery