Effects of Combined Blue and Red Home-Based Light Therapy on Sleep in Adults With Self-Reported Sleep Difficulties

IMPACT OF LIGHT THERAPY ON SLEEP AND PERFORMANCE

The goal of this intervention is to learn if a combination of morning blue light and evening red light therapy can improve sleep quality in adults with subclinical sleep complaints (non-diagnosed difficulty initiating or maintaining sleep).

The main questions it aims to answer are:

Does combined morning blue light and evening red light therapy reduce sleep onset latency (the time it takes to fall asleep) and improve sleep efficiency? Does this light therapy intervention improve subjective alertness upon awakening? Researchers will compare each participant's objective and subjective sleep data during a 7-day baseline (habitual routine) with their data during a 7-day light therapy intervention to assess whether light therapy improves sleep and daytime alertness.

Study Overview

• Status: Completed
• Conditions: Sleep
• Intervention / Treatment: Other: LED portable light therapy bulb

Detailed Description

Average sleep duration in American adults has decreased by nearly two hours over the last century, and the CDC has declared insufficient sleep a "public health problem." Inadequate sleep is linked to seven of the leading causes of death in the United States and contributes to significant economic loss through reduced productivity and accidents. While pharmacologic aids are commonly used by those with subclinical sleep issues, these often result in dependency and side effects like daytime drowsiness. Consequently, there is a clear need for non-pharmacologic interventions that can improve sleep quality and daytime alertness.

Visible light is the primary driver for synchronizing the human biological clock to the 24-hour solar cycle. Within the visible spectrum, short-wavelength "blue" light is a potent synchronizer that enhances alertness and resets circadian rhythms. Conversely, long-wavelength "red" light mimics the natural light environment of sunset and firelight; it minimally suppresses melatonin, making it less disruptive to the biological night. Despite evidence supporting light therapy for diagnosed sleep disorders, its effectiveness in individuals with subclinical sleep issues-a much larger portion of the population-remains largely unknown.

The overall objective of this study is to examine whether a combination of morning blue light and evening red light exposure can serve as an effective countermeasure for poor sleep quality and daytime fatigue. The central hypothesis is that this dual-light intervention will improve both objective and subjective sleep quality and increase subjective alertness upon awakening in adults with subclinical sleep complaints.

To test this hypothesis, the investigators will conduct a within-subject consecutive design study in 25 adults (aged 18+). Participants will first complete a 7-day baseline period to establish their habitual sleep patterns (Control condition). This is followed immediately by a 7-day intervention period (Treatment condition) consisting of 2 hours of morning blue light exposure and 2 hours of evening red light exposure. Sleep will be monitored objectively via 24-hour wrist-worn actigraphy and subjectively via daily sleep logs and the Leeds Sleep Evaluation Questionnaire (LSEQ). Subjective alertness and sleepiness will be assessed daily using the Karolinska Sleepiness Scale (KSS) and Visual Analog Scales (VAS).

Completion of this study will help bridge the gap in literature regarding light therapy's efficacy for subclinical populations. By identifying a non-pharmacological tool to improve sleep onset and morning alertness, this research aims to provide practical applications for lighting design and public health strategies to combat the risks of insufficient sleep.

• Study Type: Interventional
• Enrollment (Actual): 20
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Colorado
    • Fort Collins, Colorado, United States, 80523
      • Colorado State University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Adults age 18 and older
• Subclinical complaints of disrupted sleep or poor sleep quality
• a score of 3 or greater on the Pittsburgh Sleep Quality Index (PSQI)

Exclusion Criteria:

• Younger than 18 years of age,
• Complaints of disrupted or poor sleep with a PSQI score of less than 2
• Previously diagnosed clinical sleep disorder, such as insomnia or Circadian Rhythm Sleep Disorder (CRSD)
• Employment in evening, night, or rotating shifts
• Engagement in irregular sleep patterns that are not aligned with the biological night
• Inability to comply with the study protocol and at-home study requirements

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: LED Light Therapy; Participants in this single-arm study follow a within-subject consecutive design. All participants complete a 7-day baseline period (Control) following their habitual routine, followed immediately by a 7-day intervention period (Treatment). The intervention consists of: Morning Exposure: 2 hours of short-wavelength blue light exposure immediately upon waking. Evening Exposure: 2 hours of long-wavelength red light exposure during the 2 hours prior to the participant's anticipated bedtime. The primary goal of this arm is to assess the impact of this dual-light protocol on objective sleep onset latency and subjective morning alertness compared to the participant's own baseline data.

Other: LED portable light therapy bulb; Unlike studies that use only bright white light or single-wavelength blue light, this intervention combines morning short-wavelength (blue) light with evening long-wavelength (red) light. This study specifically targets individuals with "subclinical" sleep complaints-those with a Pittsburgh Sleep Quality Index (PSQI) score >1-rather than patients already diagnosed with clinical insomnia or Circadian Rhythm Sleep Disorders. The protocol requires a precise 4-hour daily total exposure (2 hours in the morning and 2 hours in the evening), which is more intensive than many standard 30-minute light box protocols. This is an at-home intervention where participants use portable lamp mounting options to integrate 4 hours of therapy into their regular daily activities, rather than receiving treatment in a controlled laboratory setting.; Other Names: red light; light therapy; Blue light

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Sleep Onset Latency	Sleep Onset Latency (SOL) is the amount of time (measured in minutes) it takes a participant to fall asleep after getting into bed. This will be measured objectively using a 24-hour wrist-worn actigraphy device. The study will compare the average SOL during the 7-day habitual baseline period (Control) to the average SOL during the 7-day light therapy intervention period (Treatment) to assess the efficacy of the dual-spectrum light exposure.	Average of 7 days during the Control phase (Days 1-7) and average of 7 days during the Treatment phase (Days 8-14).

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Total Sleep Time	Total Sleep Time (TST) is defined as the actual amount of time spent sleeping during the primary sleep episode, excluding any time spent awake after sleep onset. The study will compare the average TST during the 7-day habitual baseline period (Control) to the average TST during the 7-day light therapy intervention period (Treatment) to determine if the dual-spectrum light exposure increases overall sleep duration.	Average of 7 days during the Control phase (Days 1-7) and average of 7 days during the Treatment phase (Days 8-14).
Subjective Morning Alertness	Subjective alertness will be assessed using a 100-mm Visual Analog Scale (VAS) for alertness. Participants mark a position on a line where 0 represents "not at all alert" and 100 represents "extremely alert". Changes will be calculated by comparing the average morning scores (completed upon waking) during the 7-day baseline to the average scores during the 7-day intervention.	Daily upon awakening for 15 days.

Collaborators and Investigators

• Sponsor: Colorado State University
• Investigators: Principal Investigator: Josiane L Broussard, PhD, Colorado State University

Publications and helpful links

Helpful Links

• Josiane Broussard's Bibliography

Study record dates

Study Major Dates

• Study Start (Actual): July 9, 2024
• Primary Completion (Actual): July 7, 2025
• Study Completion (Actual): July 7, 2025

Study Registration Dates

• First Submitted: February 17, 2026
• First Submitted That Met QC Criteria: March 6, 2026
• First Posted (Actual): March 11, 2026

Study Record Updates

• Last Update Posted (Actual): March 12, 2026
• Last Update Submitted That Met QC Criteria: March 10, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: sleep; phototherapy; sleep quality; actigraphy; light therapy; blue light exposure; red light exposure
• Additional Relevant MeSH Terms: Nervous System Diseases; Mental Disorders; Sleep Wake Disorders; Sleep Disorders, Intrinsic; Dyssomnias; Sleep Initiation and Maintenance Disorders; Therapeutics; Physical Phenomena; Electromagnetic Phenomena; Magnetic Phenomena; Electromagnetic Radiation; Radiation; Light; Optical Phenomena; Radiation, Nonionizing; Phototherapy; Blue Light; Red Light
• Other Study ID Numbers: 5775

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No