Using CBT-I principles, participants will receive a four-week intervention delivered through a chatbot. The self-administered intervention is comprised of personalized behavioral prescriptions based on stimulus control principles and sleep schedule modification goals using sleep efficiency (SE) criteria. Participants are allowed to self-adjust expectations and make realistic decisions on sleep schedules. Other CBT-I components will be used as on-demand content. The chatbot will facilitate sleep goal setting with the participant, communicate weekly behavioral prescription and CBT-I educational modules, collect sleep diary and provide adaptive feedback and reactive services (e.g. Q&A conversations) 24/7.

Personalized intervention algorithms will be developed based on CBT-I guidelines, focus group data, individual sleep baseline information and self-reported prioritized sleep goals. The CBT-I intervention will focus on principles of sleep restriction and stimulus control, with other CBT-I components used as on-demand content. The sleep chatbot system will facilitate sleep goal-setting with the participant and communicate weekly behavioral prescriptions and educational modules. After baseline data collection, the research coordinator will provide intervention orientation and set up the first-week sleep modification goal during the in-person/Zoom meeting. Sleep modification goals in the remaining weeks will be developed through the participant-chatbot interaction. The Chatbot system will send sleep-related information and behavioral reminders/feedback based on the interactive conversation with participants. Participants will also complete a sleep diary prompted by a chatbot.

The total amount of sleep time (hours) will be estimated each night for seven consecutive days using a wrist-worn ActiGraph GT9X Link. The average sleep time over a week will be used in data analysis.

Sleep efficiency (percentage of time spent asleep while in bed) will be estimated each night for seven consecutive days using a wrist-worn ActiGraph GT9X Link. The average sleep efficiency over a week will be used in data analysis. This variable indicates sleep quality.

Sleep time and awakening time will be estimated for seven consecutive days using a wrist-worn ActiGraph GT9X Link. Mid-sleep time each night refers to the mid-point between sleep time and awakening time. Intra-individual variability in midsleep times will be calculated as the standard deviation of the mid-sleep time over a week for each participant. This variable reflects the regularity of sleep, with higher values showing greater irregularity.

The Insomnia Severity Index is composed of 7 items measuring insomnia-related sleep disturbance. and daytime dysfunction. The seven answers are added up to get a total score (0-28), with higher scores indicating severer insomnia.

The total number of metabolic syndrome components, including high waist circumference, high blood pressure, high fasting triglycerides and glucose, and low HDL, will be calculated to indicate metabolic health (higher value, worse metabolic health). A point-of-care test will provide the fasting glucose and cholesterol panel.

A self-assessment questionnaire, Horne and Ostberg Morningness/Eveningness Questionnaire, will be used to determine morningness-eveningness in circadian rhythms---the degree to which respondents are active and alert at certain times of the day. The scale requires between 10 and 15 min for completion. The sum gives a score ranging from 16 to 86; scores of 41 and below indicate "evening types", scores of 59 and above indicate "morning types", and scores between 42-58 indicate "intermediate types".