Morning Bright Light Therapy and Daytime Functioning in University Students

NCT07685262 | Recruiting

• 2 other identifiers: HSEARS20240430005P0050050
• Study Type: interventional
• Target: 153
• Locations: 1 country
• Sites: 1

Brief Summary

This study tests whether a week of morning bright light therapy changes how well healthy young adults sleep and how alert, positive, and mentally sharp they feel during the day. Morning light is the body's main signal for keeping its internal clock and sleep-wake timing on track. Many university students keep irregular hours and spend most of the day indoors, where light is far dimmer than daylight. This study asks whether adding a short, bright morning light session can help. Each participant takes part for two weeks. For one week they use a bright light box for 30 minutes each morning, shortly after waking; for the other week they keep their usual lighting. The order of the two weeks is decided at random, and each person serves as their own comparison. Throughout both weeks, sleep is tracked with a wrist-worn Fitbit and a short daily diary. Participants also rate their sleepiness and mood, complete brief computer-based attention and memory tasks, and take part in a short interview at the end about their experience. The study compares the bright-light week with the usual-light week to see whether morning bright light improves sleep regularity and efficiency, reduces daytime sleepiness, lifts mood, or affects thinking performance. The trial is being conducted in waves; a first wave has completed and a second wave is planned, pending additional funding.

Conditions

Sleep; Circadian Rhythm; Mood; Cognition; Daytime Sleepiness; Healthy Volunteers

Keywords

Bright light therapy; Melanopic illuminance; Morning light exposure; Sleep regularity; Sleep efficiency; Daytime alertness; Crossover trial; University students; Wearable sleep tracking; Karolinska Sleepiness Scale

Outcome Measures

Primary Outcomes (4)

• Sleep regularity

  Regularity of sleep timing derived from wrist-worn Fitbit actigraphy and a daily sleep diary (e.g., day-to-day variability in sleep onset and offset). Condition-week values are compared between the bright-light week and the usual-light week.

  Recorded continuously across each 1-week condition (bright-light week and usual-light week).

• Daytime sleepiness (Karolinska Sleepiness Scale)

  Subjective daytime sleepiness rated on the 9-point Karolinska Sleepiness Scale (KSS) at fixed times of day. Condition-week values are compared between the bright-light week and the usual-light week.

  Assessed daily at fixed times across each 1-week condition (bright-light week and usual-light week).

• Positive affect (PANAS Positive Affect subscale)

  Positive affect measured with the Positive and Negative Affect Schedule (PANAS) positive-affect subscale. Condition-week scores are compared between the bright-light week and the usual-light week.

  End of each 1-week condition (bright-light week and usual-light week).

• Cognitive performance (computer-based battery)

  Objective cognitive performance on a computer-based battery (Stroop, Flanker, Corsi block-tapping, and verbal span tasks). Condition-week performance is compared between the bright-light week and the usual-light week.

  End of each 1-week condition (bright-light week and usual-light week).

Study Arms (2)

Morning Bright Light Therapy

EXPERIMENTAL

During this one-week condition, participants self-administer a 30-minute session of 10,000 lux bright light (melanopic equivalent daylight illuminance ≈ 8,989 lux) each morning, approximately 30 minutes after waking, using a standard light therapy lamp positioned per manufacturer guidance.

Device: Bright light therapy (10,000 lux light box)

Usual Light (Control)

NO INTERVENTION

During this one-week condition, participants maintain their usual indoor lighting and morning routine without the light therapy lamp.

Interventions

Bright light therapy (10,000 lux light box) DEVICE

Self-administered 30-minute session of 10,000 lux (photopic) bright light each morning, approximately 30 minutes after waking, for one week, using a standard 10,000-lux light therapy lamp positioned per manufacturer guidance. Stimulus characterized in melanopic units (melanopic equivalent daylight illuminance ≈ 8,989 lux).

Morning Bright Light Therapy

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Enrolled university student
• Aged 18 years or older
• Generally healthy, with no diagnosed sleep disorder (sleep quality screened using the Pittsburgh Sleep Quality Index)
• Residing in shared student housing

You may not qualify if:

• Diagnosed insomnia or other diagnosed sleep disorder
• Other medical, psychiatric, or neurological condition that could affect sleep, mood, or cognition

Sponsors & Collaborators

• The Hong Kong Polytechnic University: lead
• Northumbria University: collaborator

Study Sites (1)

The Hong Kong Polytechnic University

Hung Hom, Hong Kong

RECRUITING

MeSH Terms

Conditions

Disorders of Excessive Somnolence

Interventions

Ultraviolet Therapy

Condition Hierarchy (Ancestors)

Sleep Disorders, Intrinsic; Dyssomnias; Sleep Wake Disorders; Nervous System Diseases; Mental Disorders

Intervention Hierarchy (Ancestors)

Phototherapy; Therapeutics

Central Study Contacts

Cehao Yu, PhD

CONTACT

+852 3400 3012; cehao.yu@polyu.edu.hk

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: BASIC SCIENCE
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Research assistant professor

Model Details: Randomized within-subject crossover trial. Each participant completes two consecutive 1-week conditions - morning bright light therapy and usual-light control - in counterbalanced (randomized) order with no washout period. Each participant serves as their own control; mixed-effects analyses include condition, period, and sequence terms.

Study Record Dates

• First Submitted: June 29, 2026
• First Posted: July 6, 2026
• Study Start: May 1, 2024
• Primary Completion (Estimated): June 30, 2028
• Study Completion (Estimated): June 30, 2028
• Last Updated: July 6, 2026

Record last verified: 2026-06

Locations

HK (1)