New app aims to fix your sleep with personalized tips

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion criteria: * Adults aged 18 to 65 years living in Hong Kong * Chinese language fluency and literacy * Experiencing ≥1 sleep or circadian problems for 3 months based on the Sleep and Circadian Problems Interview, an adapted version of the Insomnia Interview Schedule (i.e., time needed to fall asleep ≥30 minutes for ≥3 nights per week, wake after sleep onset ≥30 minutes for ≥3 nights per week, \<6-hour sleep per night or ≥9-hour sleep per night per 24-hour period for ≥3 nights per week, variability in the sleepweek schedule ≥2.78 hours within a week, and falling asleep after 2:00 AM on ≥3 nights per week) * One or more PROMIS-Sleep Disturbance (PROMIS-SD) item scores ≥4 after reverse scoring * Having adequate opportunity and circumstances for sleep to occur * Installing the JITAI app in an Internet-enabled mobile device (iOS or Android operating system) * Are willing to provide informed consent and comply with the trial protocol. Exclusion Criteria: * Involving in any psychological treatment for sleep disturbances in the past 6 months * Self-report of a significant untreated severe mental illness (e.g., bipolar disorder, psychotic disorder) * Presence of medical or cognitive disorder(s), or side effects of medication that contribute significantly to sleep or circadian problems or make participation challenging based on the team's clinical judgement * Working night shift (\>2 nights per week) in the past 3 weeks (i.e., regularly scheduled work from 12AM to 6AM) * Pregnancy or breastfeeding * Having a medical or psychiatric condition where sleep restriction is deemed unsuitable due to potential worsening of the condition Other Criteria: * Individuals who have sleep apnoea or periodic limb movement disorder commonly experience co-occurring insomnia will be included in the study due to the potential benefits they may derive from TranS-C * To allow for greater generalisability, this study will not exclude those with mental disorders whose conditions are stable based on the research team's judgement * If serious suicidal risk (i.e., Patient Health Questionnaire Item 9 score \>2) is identified, the participant will be referred to the PA (a clinical psychologist) for further assessment and professional mental health services, if needed * Medication use and changes will be recorded.