The investigators are performing this research study to understand the role of sleep disturbance on the incidence/severity of delirium after surgery. The investigators will study the brain using a polysomnography device (PSG), which records the brain's electrical activity during sleep.

During this study, PSG recordings will be collected and a sleep questionnaire will be administered to participants on the night before surgery in order to establish level of preexisting sleep disturbance. Delirium assessments will be conducted during the postoperative period. On postoperative days 0 and 1, blood will be collected for analysis. Further cognitive, quality of life and pain questionnaires will be administered perioperatively.

Inclusion Criteria:

• Over 60 years of age
• Inpatient and scheduled for surgical procedure at MGH

Exclusion Criteria:

• Blindness, deafness or the inability to speak English
• Inability to provide informed consent

Objective Drop Criteria

• Post-operative intubation greater than 24 hours

Inpatients over the age of 60 scheduled for a surgical procedure at MGH

38 Patients enrolled in the study. 32 Patients completed the baseline assessment.

Adverse event data was collected form the time the patient was enrolled to the completion of the follow-up assessment at 30 days.

This study is an observational study, not an interventional study. Thus, all adverse events patients encounter during this time period would not be related to the research study.

Adverse events and other events were determined by regular chart review.

The quality of many of the PSG recordings was poor and not interpretable. After patients enrolled, many withdrew at the time the PSG was to be placed. So, sleep was recorded for fewer patients. Blood was not analyzed.