The purpose of this study is to determine whether an intravenous infusion of dexmedetomidine administered to surgical patients intra-operatively will improve the characteristics of sleep post-operatively.

Physiological similarities exist between the anesthetized state and sleep. Pathways within the brain controlling sleep and wakefulness are also affected by anesthesia. One significant difference between the states of anesthesia and sleep is the ability to respond whenever a relatively mild stimulus is applied, e.g. verbal command or gently shaking. Interestingly, this feature of arousability is seen when dexmedetomidine is used for sedation but is absent when alternative intravenous anesthetic agents, e.g. propofol, are used to provide similar degree of sedation. Recent studies have shown that dexmedetomidine acts on receptors located within the locus ceruleus, which are responsible for both sleep and anesthesia.

During a recent study volunteers received an infusion of dexmedetomidine during the afternoon prior to remaining under study conditions for the duration of the night. The study was not designed to measure sleep but anecdotal reporting from the participants suggested that they were able to resume their normal day's activities whilst the subject receiving placebo felt extremely fatigued from lack of sleep. This prompted the establishment of a pilot study to determine if dexmedetomidine could provide restorative sleep to people under disturbed sleep conditions i.e. postoperative patients.

Inclusion Criteria:

• scheduled to undergo elective lower extremity orthopaedic surgery (free vascular fibular graft)
• ASA 1 or 2
• Body Mass Index 20 - 30
• Procedure to be done under combined epidural and general anesthesia

Exclusion Criteria:

• Sleep disturbance
• Insomnia
• Sleep apnea
• Female (pregnant)
• Contra-indication to placement of epidural anesthesia