The aim of this study is to determine if suvorexant can help treat the severity of insomnia and improve metabolic health in midlife women who had both insomnia and indicators of metabolic syndrome.

The purpose of this research study is to investigate if suvorexant can help treat the severity of insomnia (a chronic sleep disorder) in midlife women and to learn whether improvement in insomnia symptoms is linked with improvement in metabolic health. This is a double-blind, randomized placebo-controlled crossover trial. Study procedures are conducted over a 14-week period (2-week screening period, 4-week treatment period [Block 1], 4-week washout, and 4-week treatment period [Block 2]). During each treatment block, participants take a daily pill - during one block, they take suvorexant and during the other block, they take a placebo (randomized to the order).

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

Four weeks for each intervention