Digital Sleep Therapy for Older Adults With Cognitive Impairment

Inclusion Criteria: * Aged 50 years and older * Insomnia Severity Index score ≥10 * Self-reported subjective cognitive impairment as defined as moderate subjective cognitive complaints (i.e. answers YES to have cognitive concerns OR thinking and memory skills are worse than same-age peers on the online screening) * English speaking * Access to a smartphone and willingness/proficiency to use a mobile app for healthcare * Able to give informed online consent Exclusion Criteria: * Neurological (e.g. Parkinson's, epilepsy) and major psychiatric disease (e.g. current major depression), dementia, history of cerebrovascular events (stroke, TIA); history of head injury with loss of consciousness \> 30mins; * Self-reported jetlag symptoms due to travel in the last 7 days; * Current illicit substance use or alcohol intake suggestive of a hazardous or harmful pattern; * Shift-work; * Medical conditions with known effects on cognition and sleep (e.g. cancer with chemotherapy); * Diagnosed obstructive sleep apnoea, or other sleep disorder including REM Sleep Behaviour Disorder, Restless Legs Syndrome or Narcolepsy.