Investigating the Effects of Evening Light Exposure on Melatonin Suppression, Alertness and Nocturnal Sleep

Investigating the Effects of Evening Light Exposure on Melatonin Suppression, Alertness and Nocturnal Sleep.

The timing and quality of sleep is governed by environmental and physiologic factors. Environmental factors, especially ambient lighting can impact the circadian system and alter the timing and structure of sleep. Light exposure can also acutely alter neural activation state and impair sleep. These effects all demonstrate marked sensitivity to short-wavelength blue light with maximal sensitivity in the 460-480 nm range. The alerting effects of blue light in the evening persist for at least 3-4 hours after the lights are turned off, and can disturb subsequent sleep. Avoiding these deleterious effects of light exposure prior to sleep on subsequent sleep would be beneficial to sleep quality and potentially health.

The investigators will compare the effects of two light sources, equated for visual stimulus (lux), on multiple non-visual responses to light. The investigators will compare a 90 lux exposure of a commercially available Compact Fluorescent Light (CFL) with a novel LED white light source that is depleted in the short-wavelength visible range (Biological Illumination LCC, FL). In a within-subject design, the investigators will test the hypotheses that exposure to a blue-depleted LED as compared to a CFL exposure at (1) 90 lux or (2) 50 lux will cause significantly:

1. Less melatonin suppression between melatonin onset and bedtime;
2. Less subjective and objective alerting responses before bedtime;
3. Less disruption of nocturnal sleep structure and quality.

Study Overview

• Status: Completed
• Conditions: Non-visual Photoreception
• Intervention / Treatment: Device: Visible light

• Study Type: Interventional
• Enrollment (Actual): 33
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Massachusetts
    • Boston, Massachusetts, United States, 02115
      • Brigham and Women's Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 30 years (Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

(i) Aged between 18-30 years to reduce the confounding effects of lens aging on the transmission of light to the retina;

(ii) Non-smoking for at least 6 months;

(iii) Healthy (no medical, psychiatric or sleep disorders);

(iv) No clinically significant deviations from normal in medical history, vital signs, physical examination, blood chemistry and hematology, urine chemistry and ECG;

(v) Women of childbearing potential must agree to use an acceptable method of birth control, and must have a negative urine pregnancy test;

(vi) Body mass index of > 18 or < 30 kg/m2;

(vii) No drugs or medication likely to affect sleep or alertness, as determined by the investigators;

(viii) Habitual caffeine consumption < 300mg per day on average;

(ix) Habitual alcohol consumption < 10 alcoholic units per week on average.

Exclusion Criteria:

(i) History of alcohol or substance abuse;

(ii) Positive result on drugs of abuse screening;

(iii) Current or past history of sleep disorders, including but not limited to obstructive sleep apnea, or any significant sleep complaint;

(iv) Psychiatric disorder;

(v) Recent acute or chronic medical disorder, including but not limited to hepatic impairment and severe chronic obstructive pulmonary disease;

(vi) Visual disorder, including but not limited to color blindness, or family history of glaucoma;

(vii) History of intolerance or hypersensitivity to melatonin or melatonin agonists;

(viii) Pregnancy or lactation;

(ix) Shift work;

(x) Transmeridian travel (2 or more time zones) in past 2 months;

(xi) Any other reason as determined by the Principal Investigator.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Factorial Assignment
• Masking: Single

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Compact Fluorescent Light 90 lux; 90 lux exposure of a commercially available Compact Fluorescent Light (CFL).	Device: Visible light; We will compare the effects of two light sources, equated for visual stimulus (lux), on multiple non-visual responses to light including melatonin suppression before bedtime. We will compare a 90 lux exposure of a commercially available Compact Fluorescent Light (CFL) with a novel LED white light source that is depleted in the short-wavelength visible range (Biological Illumination LCC, FL).
Experimental: Blue-depleted LED light 90 lux; 90 lux exposure of a novel LED white light source that is depleted in the short-wavelength visible range (Biological Illumination LCC, FL).	Device: Visible light; We will compare the effects of two light sources, equated for visual stimulus (lux), on multiple non-visual responses to light including melatonin suppression before bedtime. We will compare a 90 lux exposure of a commercially available Compact Fluorescent Light (CFL) with a novel LED white light source that is depleted in the short-wavelength visible range (Biological Illumination LCC, FL).
Active Comparator: Compact Fluorescent Light 50 lux; 50 lux exposure of a commercially available Compact Fluorescent Light (CFL).	Device: Visible light; We will compare the effects of two light sources, equated for visual stimulus (lux), on multiple non-visual responses to light including melatonin suppression before bedtime. We will compare a 90 lux exposure of a commercially available Compact Fluorescent Light (CFL) with a novel LED white light source that is depleted in the short-wavelength visible range (Biological Illumination LCC, FL).
Experimental: Blue-depleted LED light 50 lux; 50 lux exposure of a novel LED white light source that is depleted in the short-wavelength visible range (Biological Illumination LCC, FL).	Device: Visible light; We will compare the effects of two light sources, equated for visual stimulus (lux), on multiple non-visual responses to light including melatonin suppression before bedtime. We will compare a 90 lux exposure of a commercially available Compact Fluorescent Light (CFL) with a novel LED white light source that is depleted in the short-wavelength visible range (Biological Illumination LCC, FL).

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Melatonin Suppression	Melatonin suppression is measured as the percentage of melatonin AUC relative to the AUC measured in dim light on the previous day. AUC was calculated during the 6 h of light exposure and the corresponding 6-h interval 24 hours earlier. Higher values indicate more light-induced melatonin suppression.	6-h constant posture interval of the light exposure

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Sleep Structure	Sleep efficiency assessed by polysomnography. Sleep efficiency refers to the percentage of time a person sleeps, in relation to the amount of time a person spends in bed trying to sleep. The percentage is calculated by dividing the Total Sleep Time by the Total Time in Bed.	8-h time in bed immediately following CFL/LED light exposure.
Sleep Quality	Self-reported sleep quality was assessed using a post sleep questionnaire. Score on subjective scale range 1-7, higher scores indicate higher sleep quality.	First morning after 8-h time in bed immediately following CFL/LED light exposure.
Subjective Alerting Response	Self-reported sleepiness measured during the light exposure using the Karolinska Sleepiness Scale (KSS). Range of scores 1-9, higher score indicate higher subjective sleepiness. Measures were taken hourly throughout the 6-hour constant posture interval of the light exposure and then averaged to calculate a single value per participant.	6-h constant posture interval of the light exposure.
Objective Alerting Response	Mean reaction time assessed using the 10-minute psychomotor vigilance test. Higher numbers indicate slower reaction times indicating less alertness. Measures were taken hourly throughout the 6-hour constant posture interval of the light exposure and then averaged to calculate a single value per participant.	6-h constant posture interval of the light exposure

Collaborators and Investigators

• Sponsor: Brigham and Women's Hospital
• Collaborators: Biological Illumination LLC
• Investigators: Principal Investigator: Steven W Lockley, Ph.D., Brigham and Women's Hospital; Harvard Medical School

Study record dates

Study Major Dates

• Study Start: August 1, 2012
• Primary Completion (Actual): March 1, 2014
• Study Completion (Actual): March 1, 2014

Study Registration Dates

• First Submitted: April 24, 2012
• First Submitted That Met QC Criteria: April 25, 2012
• First Posted (Estimate): April 26, 2012

Study Record Updates

• Last Update Posted (Actual): September 14, 2021
• Last Update Submitted That Met QC Criteria: September 10, 2021
• Last Verified: September 1, 2021

More Information

Terms related to this study

• Keywords: Melatonin; Sleep; Light; Alertness; Circadian Rhythms
• Other Study ID Numbers: 2011-P-002834

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