Participants will receive guidance to restrict daily food intake to a consistent 10-hour eating window.

Time of calorie consumption (h:m)

The Morningness-Eveningness Questionnaire (MEQ) is a 19-item self-report assessment used to determine an individual's circadian preference (chronotype), ranging from morning-type to evening-type. Scores range from 16 to 86, with higher scores indicating morningness and lower scores indicating eveningness.

The PHQ-9 is a 9-item, self-report questionnaire used to screen for and measure the severity of depression in clinical trials. It covers the 9 diagnostic criteria for major depressive disorder based on the DSM-IV. Total scores range from 0 to 27, with higher scores indicating higher levels of depression.

The PDQ-D5 is a self-report questionnaire assessing subjective cognitive impairment. It includes five items covering four subscales: Attention/Concentration, Retrospective Memory, Prospective Memory, and Planning/Organization. The total score is the sum of the five items, ranging from 0 to 20. Higher scores indicate greater perceived cognitive deficits, while lower scores indicate fewer problems.

The Pittsburgh Sleep Quality Index (PSQI) is a 19-item self-report questionnaire assessing sleep quality and disturbances over a one-month interval. It measures seven components (quality, latency, duration, efficiency, disturbances, medication, dysfunction) to produce a global score from 0 to 21, where higher scores indicate poorer sleep quality.

Formula: Total participants enrolled / enrollment time window, with higher numbers indicating better recruitment.

Formula: (number of participants that complete the study / number of participants that enrolled) x 100, reported as percentage with higher numbers indicating higher retention.

The missing data rate is defined as the percentage of expected data points for primary outcomes (e.g., daily food logs, daily actigraphy wearing, and survey responses) that were not collected or were unusable at the final study visit. Calculation: (Number of missing data points / Total number of expected data points across all enrolled participants) × 100 reported as a percentage with higher values indicating more missing data. Note: This includes data missing due to participant withdrawal or non-response to specific survey items.

Adherence to the Mediterranean Diet is assessed using the validated 13-item Mediterranean Diet Adherence Screener (13-MEDAS). The questionnaire evaluates the consumption frequency of Mediterranean dietary staples (e.g., olive oil, vegetables, fruits, nuts, fish, legumes) and frequency of unhealthy food choices (e.g., animal fats, sugar-sweetened beverages). Each item is scored 0 or 1. The total score ranges from 0 to 13, with higher scores indicating greater adherence.

Using the time of first and last caloric intake of the day, time-restricted eating adherence is calculated as the percentage of days where all food was consumed within the designated 10 h time window.

Participant-reported manageability of diet changes on study team generated Intervention Acceptability Survey. A single item ("The Mediterranean diet changes were manageable") will be scored on a 5-point Likert scale (1 = Strongly Disagree, 5 = Strongly Agree). Data for all participants reported. Higher values indicate diet content modifications were more manageable.

Participant-reported manageability of diet changes on study team generated Intervention Acceptability Survey. A single item ("The time restriction on calorie intake was manageable") will be scored on a 5-point Likert scale (1 = Strongly Disagree, 5 = Strongly Agree). Data reported for Group 2 only (Mediterranean Diet + Time-Restricted Eating). Higher values indicate diet timing modifications were more manageable.

A single-item assessment of the overall change in depression since study entry. Scale: 1 = Very Much Worse, 2 = Much Worse, 3 = Minimally Worse, 4 = No Change, 5 = Minimally Improved, 6 = Much Improved, 7 = Very Much Improved. Higher scores indicate greater improvement.

A single item ("The dietary changes made during the study had a positive impact on my sleep") will be scored on a 5-point Likert scale (1 = Strongly Disagree, 5 = Strongly Agree). Higher scores indicate a more positive perceived impact.

A single item ("The dietary changes made during the study had a positive impact on my metabolic health") will be scored on a 5-point Likert scale (1 = Strongly Disagree, 5 = Strongly Agree). Higher scores indicate a more positive perceived impact.

A single item ("The dietary changes made during the study had a positive impact on my overall health") will be scored on a 5-point Likert scale (1 = Strongly Disagree, 5 = Strongly Agree). Higher scores indicate a more positive perceived impact.

A single-item assessment of the participant's intention to continue the intervention diet after the study concludes ('I plan to maintain dietary changes from the study moving forward') will be scored on a 5-point Likert scale (1 = Strongly Disagree, 5 = Strongly Agree). Higher scores indicate a higher intent to maintain the dietary changes.

The ratio of the variance of the average 24-hour activity profile to the variance of the overall 24-hour data. Actigraphy is collected over 2 weeks and averaged to create a single, representative 24-hour profile. Interdaily Stability values range from 0 to 1, where 0 indicates a total lack of stability and 1 indicates perfect stability. Lower values suggest fragmented, weak, or disrupted circadian rhythms. Change in Interdaily Stability will be calculated with baseline (2 week period) and end of intervention (2 week period).

The PHQ-9 is a 9-item, self-report questionnaire used to screen for and measure the severity of depression in clinical trials. It covers the 9 diagnostic criteria for major depressive disorder based on the DSM-IV. Total scores range from 0 to 27, with higher scores indicating higher levels of depression. Change in PHQ9 will be calculated with baseline (week 2) and end of intervention (week 10).

The PDQ-D5 is a self-report questionnaire assessing subjective cognitive impairment. It includes five items covering four subscales: Attention/Concentration, Retrospective Memory, Prospective Memory, and Planning/Organization. The total score is the sum of the five items, ranging from 0 to 20. Higher scores indicate greater perceived cognitive deficits, while lower scores indicate fewer problems. Change in PDQ-D5 will be calculated with baseline (week 2) and end of intervention (week 10).

The Pittsburgh Sleep Quality Index (PSQI) is a 19-item self-report questionnaire assessing sleep quality and disturbances over a one-month interval. It measures seven components (quality, latency, duration, efficiency, disturbances, medication, dysfunction) to produce a global score from 0 to 21, where higher scores indicate poorer sleep quality. Change in PSQI will be calculated with baseline (week 2) and end of intervention (week 10).