Overview
What is it?
Light therapy, also known as phototherapy, is a non-invasive and cost-effective treatment that uses specific wavelengths of light to influence brain functions. It has been shown to help with various conditions, including sleep disorders, depression, and circadian rhythm disruptions. Light therapy can be administered using devices like light boxes, lamps, or even natural sunlight.
How does it work?
Light therapy works by stimulating specialized cells in the retina called intrinsically photosensitive retinal ganglion cells (ipRGCs). These cells send signals to the brain's circadian clock, which regulates sleep-wake cycles. Morning light exposure can advance sleep timing, making it easier to fall asleep earlier, while evening light exposure can delay sleep timing. Light therapy also helps regulate melatonin production, a hormone crucial for sleep .
What are the benefits?
Light therapy has been shown to improve sleep quality, reduce insomnia symptoms, and regulate circadian rhythms. It can help with sleep maintenance, reduce wakefulness after sleep onset, and improve sleep efficiency. It is particularly effective for individuals with circadian rhythm sleep disorders, insomnia, and sleep problems related to conditions like Alzheimer’s disease or Parkinson’s disease .
Effectiveness
What does the research say?
Research shows that light therapy is effective for improving sleep, particularly for insomnia and circadian rhythm disorders. A meta-analysis of 22 studies found that light therapy significantly reduced wakefulness after sleep onset by 11.2 minutes based on actigraphy and 36.4 minutes based on sleep diaries . Another meta-analysis of 53 studies found small to medium effects on sleep problems, with larger benefits for insomnia and circadian rhythm disorders . Studies also show that combining light therapy with melatonin can enhance sleep outcomes .
Side Effects
Eye strain
Eye strain is a common side effect, often caused by prolonged exposure to bright light .
Headache
Headaches may occur, especially if the light intensity is too high or the session is too long .
Agitation
Some individuals may experience agitation or restlessness, particularly if light therapy is used late in the day .
Nausea
Nausea has been reported in a small number of cases, though it is rare .
Sedation
Sedation or drowsiness can occur, especially if light therapy is used in the evening .
Evidence
Clinical Studies & Trials
[1] Light therapy in insomnia disorder: A systematic review and meta-analysis
This meta-analysis of 22 studies found that light therapy significantly improved wakefulness after sleep onset in insomnia patients, with no worsening of other sleep measures.
View study[2] The effects of light therapy on sleep problems: A systematic review and meta-analysis
This meta-analysis of 53 studies found light therapy effective for sleep problems, particularly for circadian rhythm disorders and insomnia, with small to medium effect sizes.
View study[3] A Comprehensive Overview of the Neural Mechanisms of Light Therapy
This review explains how light therapy modulates neural circuits to improve sleep, mood, and circadian rhythms, with benefits for conditions like insomnia and Parkinson’s disease.
View study[4] Blocking nocturnal blue light for insomnia: A randomized controlled trial
This study found that wearing amber lenses to block blue light before bedtime improved sleep quality and increased total sleep time in individuals with insomnia.
View study[5] Canadian Network for Mood and Anxiety Treatments (CANMAT) 2016 Clinical Guidelines for the Management of Adults with Major Depressive Disorder: Section 5. Complementary and Alternative Medicine Treatments
This review discusses light therapy as a treatment for depression and its potential benefits for sleep, with common side effects including eye strain and headache.
View study[6] A randomized, double-blind, placebo-controlled trial of blue wavelength light exposure on sleep and recovery of brain structure, function, and cognition following mild traumatic brain injury
This study found that morning blue light exposure improved sleep timing, reduced daytime sleepiness, and enhanced cognitive function in patients with mild traumatic brain injury.
View study[7] Physician light therapy
This study explores light therapy as a method to reset circadian rhythms and improve sleep, particularly for physicians working irregular hours.
View study[8] Therapeutic potential of bright light therapy for the non-motor symptoms in Parkinson's disease
This study found that bright light therapy improved sleep quality, daytime sleepiness, and cognitive function in Parkinson’s disease patients.
View study[9] Bright light improves sleep and psychological health in shift working nurses
This study showed that bright light therapy improved sleep quality and reduced insomnia severity in shift-working nurses.
View study[10] Bright light therapy
This review discusses the use of light therapy for various conditions, including circadian rhythm sleep disorders, insomnia, and depression.
View study