Cognitive Behavioral Therapy for Insomnia as an Adjunct to Time-restricted Eating on Weight Loss in Adults With Overweight or Obesity and Chronic Insomnia

Inclusion Criteria: 1. Ethnic Chinese; 2. Age 18 years or older; 3. Fulfill the criteria of chronic insomnia defined by Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR) , which are: i. manifestation of predominant, subpar sleep quantity or quality; ii. exhibition of any sleep difficulties ranging from sleep initiation, sleep maintenance to early awakening with the inability to restore sleep. iii. concomitant presentation of significant distress or impairment, including fatigue or low energy, cognitive impairment, mood disturbance, behavioral problems, impaired occupational or academic functioning, impaired interpersonal or social functioning and negative impact on caregiver or family functioning; iv. sleep difficulty occurs at least three nights per week; v. sleep difficulty has been persistent for at least three months; and vi. sleep difficulty is not affected regardless of adequate opportunity given for sleep. 4. With Overweight or obesity: BMI ≥ 23 kg/m2 5. Weight stable for the past 3 months 6. Habitual eating window ≥ 10 hours Exclusion Criteria: 1. Known cardiovascular disease; 2. Type 1 or 2 diabetes mellitus; 3. Current use of GLP-1 receptor agonists or other prescription weight-loss medications within the past 3 months; 4. Currently on a special or prescribed diet for other reasons; 5. Currently receiving any psychological treatment for insomnia; 6. Previously received CBTI; 7. Night shift workers; 8. Breastfeeding, pregnant or trying to become pregnant; 9. Smokers.