The investigators are performing this research study to understand the role of sleep disturbance on the incidence of delirium after surgery.

Sleep is one of the most important physiological needs. Sleep disturbances have detri-mental effects on practically all systems and may thus prolong recovery of patients. Studies have documented many similarities between clinical and physiological profiles of patients with delirium and sleep disturbances (ischemia/inflammation, hypoxia, neu-rotransmitter imbalance and tryptophan/melatonin metabolism abnormalities). There is still a lack of strong evidence to support the link between poor sleep and delirium, par-ticularly in hospitalized patients, even though available studies suggest that sleep dis-turbances may be a potential key risk factor for its development, which may have a significant clinical impact.

Post operative delirium will be diagnosed using the 3D- CAM(Confusion Assessment Method) which tests for four features with a series of questions. The features include 1) acute onset and fluctuating course,2) inattention,3) disorganized thinking and 4) altered level of consciousness. Diagnosis of delirium is made if features 1 and 2 and either 3 or 4 are present.

The demographic data of the patients,type and site of surgery will be noted. Preoperative hemoglobin, serum electrolytes and blood urea will be recorded. The intraoperative factors like duration of surgery and anaesthesia,use of intravenous fluids ,blood loss, number blood units transfused and opioid use will be studied at the time of surgery. The time to emergence and extubation following the completion of surgery will be noted.

The association of various preoperative,intraoperative and postoperative factors with POD will be determined.

Inclusion Criteria:

Geriatric surgical patients ≥65 years old

Exclusion Criteria:

Patients in the central nervous system group were excluded from cardiac and neurosurgery, patients in the heart injury group were excluded from cardiac surgery, and patients who did not agree to participate in the study were excluded in all groups.

hospital based group