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NCT Number: NCT07339592

This Trial Examines How Last Meal Composition and Timing Affect Sleep Quality and Circadian Gene Expression Among Medical Residents. Recruitment Not Yet Started; Study Begins Dec 2025 and Ends Dec 2026.

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:

1. High-carbohydrate last meal (≈80% of dinner calories from carbohydrates), 2. High-protein last meal (≈40-50% of dinner calories from protein), 3. Control group consuming a balanced standard meal. Each participant will consume the assigned meal 3-4 hours before bedtime for two weeks. Sleep quality will be measured using the Pittsburgh Sleep Quality Index (PSQI) and smartwatch-derived parameters, while salivary samples collected pre- and post-intervention will be analyzed for CLOCK and BMAL1 gene expression. The study will also include dietary, anthropometric, and physical activity assessments.

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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Key information

Conditions

Sleep Quality Circadian Rhythm Dyssomnias Meal Timing Medical Residents Mental Disorders Nervous System Diseases Nutrition Intake Sleep Disorders, Intrinsic Sleep Initiation and Maintenance Disorders Sleep Wake Disorders

Age range

25 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

University of Jordan Hospital

Amman, Jordan

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Currently enrolled and working in Jordanian hospitals.
  • Not currently following a specific diet or weight-loss program.
  • Willing to comply with study protocol and intervention meals for two weeks. Provide written informed consent before participation.

Exclusion criteria

  • Presence of any chronic medical condition (e.g., diabetes, thyroid disorders, gastrointestinal, cardiovascular, or respiratory diseases).
  • Diagnosed sleep disorders, such as insomnia, sleep apnea, or restless legs syndrome.
  • Mental health disorders (stress, anxiety, or depression diagnosed or medicated).
  • Pregnancy or lactation.
  • Use of medications or herbal supplements known to affect sleep (e.g., melatonin, chamomile, ashwagandha, lavender).
  • Caffeine dependence exceeding moderate levels ( >400 mg caffeine/day).

Treatment and study plan

High-Carbohydrate Last Meal

Dietary Supplement

Dinner ≈30% daily kcal; ~80% carb; taken 3-4 h before sleep for 2 weeks

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.

Primary outcomes

  1. Change in Sleep Quality (PSQI Global Score)

    Time frame: Baseline and 2 weeks post-intervention

    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

Secondary outcomes

  1. Change in CLOCK Gene Expression

    Time frame: Baseline and 2 weeks post-intervention

    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.

  2. Change in BMAL-1 Gene Expression

    Time frame: Baseline and 2 weeks post-intervention

    BMAL-1 mRNA levels will be analyzed in the same saliva samples via real-time PCR. Changes will be compared across meal groups.

  3. Change in Total Sleep Duration

    Time frame: 1 week baseline and 2 weeks during intervention

    Total sleep duration will be objectively measured using smartwatch data and expressed as average nightly sleep duration.

    Unit of Measure: Minutes per night

  4. Change in Sleep Efficiency

    Time frame: 1 week baseline and 2 weeks during intervention

    Sleep efficiency will be calculated as the percentage of total sleep time divided by time in bed using smartwatch data.

    Unit of Measure: Percentage (%)

  5. Change in Sleep Stage Distribution

    Time frame: 1 week baseline and 2 weeks during intervention

    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 (%)

  6. Change in Average Heart Rate During Sleep

    Time frame: 1 week baseline and 2 weeks during intervention

    Average heart rate during sleep will be measured using smartwatch data. Unit of Measure: Beats per minute (bpm)

Sponsors and collaborators

Lead sponsor

University of Jordan

Other

Registry information

Official study title

CHRONO-NUTRITION INTERVENTIONS FOR IMPROVING SLEEP QUALITY: The Impact of Last Meal Composition and Timing on Sleep Quality Among Medical Residents at Hospitals

Acronym: CHRONO-MED

Important dates

Study start
2025
Primary completion
2026
Study completion
2026
First posted
Jan 14, 2026
Registry last updated
Jan 14, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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