A Novel Inhaled Formulation of Melatonin to Treat Adults With Insomnia: Efficacy Study

Inclusion Criteria: * 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. * History of subjective sleep onset latency (sSOL) ≥30 minutes on at least 3 nights per week in the previous 4 weeks. * Able to provide informed electronic consent. * Fluent English literacy. * Adults aged 55+ years old. Exclusion Criteria: * 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. * Objective cognitive decline measured by scoring ≤26 on the Montreal Cognitive Assessment (MoCA) * Regular shift work, jet lag or trans-meridian travel (over 2h time difference) in the past week before randomisation. * Pregnancy or lactation. Female participants of childbearing potential with a fertile sexual partner must have a negative serum pregnan…