Treating Insomnia and Improving Metabolic Health in Midlife Women With Insomnia

Inclusion Criteria: * Healthy women aged 40-65 years * Late perimenopausal or postmenopausal * Meets criteria for Insomnia Disorder * Elevated score on the Insomnia Severity Index (ISI) consistent with clinical insomnia * Subjective and sustained sleep disruption during screening * Hot flashes present, including at night * Pre-diabetic per American Diabetes Association guidelines or have abnormal levels of one or more atherosclerotic cardiovascular disease risk factors per American Heart Association-defined metabolic syndrome Exclusion Criteria: * Diagnosis of other primary sleep disorders * Shift worker * Frequent use of hypnotic medications * Unwillingness to refrain from taking any sleep medications during the study period * Current major depressive episode * Suicidal ideation * Lifetime history of bipolar disorder, psychosis, or other serious mental health problem * Current alcohol/substance use disorder * Current or prior diagnosis of diabetes mellitus * Use of an insulin sensitizer or a pharmacologic treatment for pre-diabetes * Extreme obesity * Current use of systemic hormonal therapies * Renal or hepatic disease * Pregnancy or breastfeeding * Recent malignancy * Recent surgery * Neurological disorder or cardiovascular disease raising safety concerns * Medical instability considered to interfere with study procedures * Concomitant medications with drug interaction or co-administration concerns * Contraindications or allergic responses to suvorexant * Recent travel across time zones * Excessive coffee or cigarette use * Unwilling to limit alcohol, nicotine, and caffeine consumption during study