The goal of this clinical trial is to explore the potential neuroprotective benefits of a dual orexin receptor antagonist (DORA) in adults with insomnia. The main questions it aims to answer are:
* Does the DORA reduce blood-based phosphorylated TAU181, in adults with insomnia, when compared to placebo * Does the DORA reduce other blood-based biomarkers of neurodegeneration, including phosphorylated TAU217, amyloid beta 40:42 ratio, Neurofilament Light Chain (NFL) and Glial Fibrillary Acidic Protein (GFAP), when compared to placebo.
Participants will:
* Take 10mg Lemborexant nightly for two weeks * Take a matching placebo nightly for two weeks * Visit the research institute for a screening visit and for an overnight visit at the conclusion of each study drug treatment (3 visits in total).
Diagnosis of insomnia disorder as defined by the DSM-5 (difficulty initiating or maintaining sleep or waking up too early for at least 3 nights per week, for at least 3 months, with adequate opportunity and circumstances for sleep and at least one daytime impairment related to the sleep difficulty) and a score ≥15 on the ISI.
Able to provide informed electronic consent.
Fluent English literacy.
Adults aged between 40-65 years.
People highly dependent on medical care as determined by a medical officer.
Untreated moderate-severe sleep apnoea as diagnosed using in-home wrist oximetry (oxygen desaturation index>15, ongoing effectively treated sleep apnoea with insomnia will be allowed).
Circadian disorders, narcolepsy, severe restless legs syndrome, and REM sleep behaviour disorder or uncontrolled psychiatric disorders.
History of attempted suicide or current suicide ideation (indicated by a score >0 on Q9 of the Patient Health Questionnaire-9) at pre-screening.