Subjects in the ketamine IV groups will receive infusions 3 times weekly for two weeks (0.5 mg/kg infused over 40 minutes on approximately days 1, 3, 5, 8, 10 and 12 of admission). The exact schedule of dates is referred to as approximate since it may need to be adjusted slightly depending on the timing of admission/weekends etc. Subjects in the midazolam group will have the same dosing schedule but will instead receive midazolam 0.045 mg/kg IV infused over 40 minutes. A sub-anesthetic dose of midazolam was chosen as an active placebo because it has CNS effects including sedation and amnestic effects, thus making it more difficult for subjects to guess which group they are in. Vital signs including pulse, respiratory rate and arterial oxygen saturation will be monitored throughout the ketamine/midazolam infusion and for one hour post-infusion as has been the standard in the published literature. If the subject experiences side effects, the protocol will allow for the infusion to be slowed to up to 90 minutes.