The study is a parallel group, double blind, randomized trial. Subjects will be recruited from individuals undergoing elective surgery for orthopedic, abdominal, urologic, gynecologic or spine reasons. Out of 92 subjects, one experimental group of 46 subjects will receive 20 mg Suvorexant beginning the first in-hospital night ("day 0") and continuing for their hospital stay. If the dose is not well tolerated (e.g., daytime sleepiness), then the dose may be decreased to 10 mg of Suvorexant.

For blinding purposes each arm will receive two tablets (two 10 mg tablets or one 10 mg tablet and a placebo). The other control group of 46 subjects will receive placebo (two tablets) and treatment as usual.

It is rare to get a good night's sleep in the hospital. Even routine patient care, including alarm systems, and too much light can lead to sleep disturbance. Failure to achieve enough high-quality sleep has been associated with decreased brain and heart function. The investigators aim to restore usual sleep patterns in hospitalized patients to have a positive influence on patient outcomes and healthcare costs. Suvorexant, the tested drug in our protocol, works on a different brain chemical system than most other sleep drugs, which may account for its ability to restore natural sleep. Suvorexant has been shown to reduce wakefulness during sleep by a reduction in long wake bouts. This reduction has a positive effect on sleep quality. In keeping with Suvorexant's established ability to decrease insomnia in outpatient settings, the investigators will assess its efficacy to improve sleep quality in the hospital environment in patients having surgery who have sleep disturbance. Suvorexant will be administered beginning on the night after surgery and through the hospitalization (it is estimated that stays will be 1-3 days; the investigators will set a maximum of 4 days). If the dose is not well tolerated (e.g., daytime sleepiness), then the dose may be decreased to 10 mg of Suvorexant. The investigators aim to study the participant's sleep patterns by using a self-wearable electroencephalography (EEG) recording device, the Sleep Profiler, and see patterns such as total sleep time or the stages of sleep such as rapid eye movement (REM), non-REM, etc. Additionally, the investigators hope to determine if concentration, attention, and general cognitive performance are improved as a result of better sleep. Promoting "natural sleep" may improve surgical recovery through the lessening of fatigue and improvements in brain health.

Inclusion criteria:

• Aged 50 years to 90 years old.
• Patients getting elective surgeries for orthopedic reasons (e.g., hip or knee replacement), abdominal surgery (e.g., hernia repair, renal cancer), urologic or gynecologic surgery, and spine surgery with a projected inpatient stay of 24 hours or longer.
• Patients experiencing insomnia characterized by difficulties with sleep onset, early morning awakening, and/or sleep maintenance three or more times weekly over a three-month period for eligibility.

Exclusion criteria:

• Patients who undergo surgery and then are admitted to intensive care.
• Coronary artery bypass graft (CABG) or other cardiac surgeries.
• Intra-cranial surgery.
• Patients taking more than 60 mg of oxycodone or it's equivalent as outpatient
• Circadian rhythm disorders.
• High score in the Geriatric Depression Scale (GDS)
• Moderate to severe dementia (failed t-MoCa)
• Severe obstructive sleep apnea (OSA) (Apnea-hypopnea index (AHI)>30 and/or screen high risk)
• Patients receiving Cytochrome P-450 (CYP3) inhibitors or inducers (Inhibitors: clarithromycin, erythromycin, diltiazem, itraconazole, ketoconazole, ritonavir, verapamil, goldenseal, and grapefruit. Inducers: phenobarbital, phenytoin, rifampicin, St. John's Wort, and glucocorticoids).
• Vulnerable populations (i.e., children, pregnant women).

Data will be shared in aggregate form. There is no plan to share individual participant data (IPD) with researchers not involved with the study design. Several posthoc analyses are being planned for retrospective analysis of the data obtained.

Raters and subjects will be blinded to treatment. At the study's completion (the last subject completes) the blind will be broken, and data will be turned over for analysis. A study physician will be available on call 24 hours to monitor patient safety issues that may arise during the hospitalization and they will have access to the blind. Furthermore, the Research Pharmacy will maintain the blind.