Time Restricted Eating in Sleep Apnea

This study involves several visits: 1\. Those participants who fulfill inclusion criteria and are not excluded by virtue of any of the exclusion criteria will be asked to come to the University of California San Diego for visit 1. At this visit, participants will fill out consent form, will have a fasting blood draw, will have vitals checked, will fill out a quality-of-life questionnaire (SF-36), will have a continuous glucose monitor (CGM) applied, and will be given an Actiwatch to wear during the baseline/screening period. Participants will also download the myCircadianClock (mCC) app, be provided a unique access code to log in, and be trained on how to use the mCC app to document food and beverages. Study coordinators will help participants download the app. This will be the beginning of the 2-week baseline/screening period. 1a. During the 2-week baseline/screening period, all participants will be asked to maintain their current lifestyle, and record all of their dietary intake (by taking photos and/or annotating all of the food/beverages they consume) with the mCC app. These data will be used to determine the participants' baseline eating window. Participants will also receive regular nudges from the mCC app (reminders and tips) and educational blogs. During baseline, participants will also continue to wear the CGM and Actiwatch. Participants are asked not to significantly change their diet (e.g., start a new diet program) at any point during the study. 2\. At the end of the screening period, participants will go to ACTRI Visit 2. There, participants will have their CGM removed and will return their Actiwatch. Participants with an eating window of ≥12 h, have sufficient logging, and pass all inclusion/exclusion criteria will be randomized to SE or TRE for intervention. All participants will meet with a dietician for a 24-hour dietary recall, will receive instruction and written information on how to follow the intervention they were assigned and to what to expect throughout the study, and will schedule future visits when possible. The TRE group will be asked to limit their food intake to a consistent, self-selected, 10 hour period daily, during which they will consume all caloric intake. Water and medications will be allowed outside this window. Otherwise, these participants will be asked to continue their normal daily routine. The SE group will be asked to continue their routine as they were. 2a. During the 12 weeks of monitored/guided intervention, all participants will continue to log all of their food and beverages into the mCC app. Every two weeks they will have a phone call or video visit with a member of the research team. At these virtual visits, participants will discuss their experience with the study intervention, including any barriers to adherence or points of clarification. 3\. At week 10 of the intervention period, participants will return for ACTRI Visit 3. At this visit, they will have a CGM applied and be provided an Actiwatch to wear for the following two weeks. They will also discuss their experience with the study. Finally, participants will be provided with a home sleep apnea test device, in order to determine OSA severity at the end of the study period. 4\. At week 12 of the intervention period, participants will return for ACTRI visit 4. At this visit, participants will repeat all assays at baseline (fasting blood draw, vitals, questionnaires, 24-h dietary recall), have their CGM removed, and return the Actiwatch. They will also provide feedback on their experience in the study, and home sleep apnea test equipment will be collected and downloaded. If participants wish, study coordinators will help them delete the mCC app from their smartphones.