Healthy Lighting Guide
Illuminating Your Health and Home
Excerpt: The Impact Of Blue Light On Health
Blue Light (400nm-490nm)
Room Light Before Bedtime May Impact Sleep Quality, Blood Pressure, and Diabetes Risk
A study led by Dr. Joshua Gooley, published in The Journal of Clinical Endocrinology & Metabolism, found that evening exposure to room light significantly impacts melatonin, a hormone vital for sleep, body temperature regulation, and blood glucose control. This effect is particularly concerning for those frequently exposed to artificial light, such as shift workers.
Study Overview
Participants: 116 healthy adults (aged 18–30)
Duration: 5 days with controlled light exposure
Method: Participants experienced either room light or dim light for eight hours before bed, and
blood samples were taken to measure melatonin levels.
Key Findings
Melatonin Onset: Evening room light delayed melatonin onset in 99% of participants, shortening melatonin duration by 90 minutes.
Night-time Suppression: During typical sleep hours, room light suppressed melatonin by over
50% in 85% of participants.
This melatonin suppression may elevate risks for health conditions such as Type 2 Diabetes and
certain Cancers. Bright, blue-enriched light was noted as particularly disruptive, mimicking natural daylight and reducing melatonin—a critical cue for sleepiness.
