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This randomized controlled trial aims to evaluate the effects of last meal composition and timing on sleep quality and circadian gene expression among medical residents in Jordanian hospitals. Sleep disturbances are common in this population due to long working hours, high stress, and irregular eating schedules. Chrono-nutrition, the science of aligning food intake with circadian rhythms, may provide a practical approach to improving sleep and overall well-being.
Participants will be randomly assigned to one of three groups:
This study has been approved by the Institutional Review Board of the University of Jordan (IRB No. 491/2025). Recruitment has not yet started. Enrollment is expected to begin in December 2025, with primary data collection completed by June 2026 and final study completion by December 2026.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| High-Carbohydrate Last Meal | Experimental | Dinner ≈30% of daily kcal; ~80% of dinner kcal from carbs; consumed 3-4 h before sleep for 2 weeks. |
|
| High-Protein Last Meal | Experimental | ≈30% of daily kcal; ~38-54% of dinner kcal from protein; consumed 3-4 h before sleep for 2 weeks. |
|
| Balanced Standard last meal | Active Comparator | Standard balanced dinner (per usual guidelines), same timing (3-4 h pre-sleep) and 2 weeks duration. |
|
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| High-Carbohydrate Last Meal | Dietary Supplement | Dinner ≈30% daily kcal; ~80% carb; taken 3-4 h before sleep for 2 weeks |
|
| Measure | Description | Time Frame |
|---|---|---|
| Change in Sleep Quality (PSQI Global Score) | Sleep quality will be assessed using the Pittsburgh Sleep Quality Index (PSQI) before and after the 2-week intervention. The PSQI total score (0-21) will quantify subjective sleep quality; higher scores indicate poorer sleep | Baseline and 2 weeks post-intervention |
| Measure | Description | Time Frame |
|---|---|---|
| Change in CLOCK Gene Expression | CLOCK mRNA expression will be measured in salivary samples collected pre- and post-intervention using RT-PCR. Relative quantification (ΔCt method) will determine expression changes. | Baseline and 2 weeks post-intervention |
| Change in BMAL-1 Gene Expression |
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Inclusion Criteria:
Exclusion Criteria:
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| Name | Affiliation | Role |
|---|---|---|
| Hadeel A Ghazzawi, professor | The University of Jordan School of Agriculture | Principal Investigator |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| University of Jordan Hospital | Amman | Jordan |
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| High-Protein Last Meal | Dietary Supplement | Dinner ≈30% daily kcal; ~38-54% protein; 3-4 h before sleep for 2 weeks. |
|
| Balanced Standard Dinner | Dietary Supplement | Standard macronutrient distribution; same timing (3-4h pre-sleep) and 2-week duration. |
|
BMAL-1 mRNA levels will be analyzed in the same saliva samples via real-time PCR. Changes will be compared across meal groups. |
| Baseline and 2 weeks post-intervention |
| Change in Total Sleep Duration | Total sleep duration will be objectively measured using smartwatch data and expressed as average nightly sleep duration. Unit of Measure: Minutes per night | 1 week baseline and 2 weeks during intervention |
| Change in Sleep Efficiency | Sleep efficiency will be calculated as the percentage of total sleep time divided by time in bed using smartwatch data. Unit of Measure: Percentage (%) | 1 week baseline and 2 weeks during intervention |
| Change in Sleep Stage Distribution | Sleep stage distribution (light, deep, and REM sleep) will be assessed using smartwatch data and expressed as percentage of total sleep time. Unit of Measure: Percentage (%) | 1 week baseline and 2 weeks during intervention |
| Change in Average Heart Rate During Sleep | Average heart rate during sleep will be measured using smartwatch data. Unit of Measure: Beats per minute (bpm) | 1 week baseline and 2 weeks during intervention |
| ID | Term |
|---|---|
| D007319 | Sleep Initiation and Maintenance Disorders |
| ID | Term |
|---|---|
| D020919 | Sleep Disorders, Intrinsic |
| D020920 | Dyssomnias |
| D012893 | Sleep Wake Disorders |
| D009422 | Nervous System Diseases |
| D001523 | Mental Disorders |
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