The goal of this clinical trial is to explore the potential benefits of an inhaled version of melatonin compared to oral melatonin tablets on adults with insomnia. The main question the trial aims to answer: is the time required for inhaled melatonin to reach peak concentration in the blood and then be eliminated from body different to that of oral melatonin tablets, in adults with insomnia?
5 participants will:
* Visit the research institute for a screening visit and for a daytime visit to take a melatonin treatment then provide blood samples over the course of 8 hours for each study drug treatment (3 visits in total) * Take 100 μg of inhaled melatonin (2 inhaler puffs) once * Take a 4 mg of oral melatonin (2 tablets) once
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.
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.