How should light therapy be administered?

How to Administer Light Therapy

Position the light source approximately 30-34 inches (about 1 meter) from the patient's eyes, ensuring the device delivers at least 2,500-10,000 lux of blue-enriched white light (460-490 nm wavelength) for 30-60 minutes during morning hours (typically 09:00-11:00 AM), with the patient's eyes open and gaze directed toward the light intermittently during the session. 1, 2, 3

Device Selection and Specifications

Light Source Requirements

• Use LED-based light boxes that emit narrow-band blue-to-green light in the 460-490 nm wavelength range, with 478 nm being optimal 1
• The device must filter out ultraviolet rays to prevent ocular damage 2, 4
• Standard therapeutic devices deliver 10,000 lux at the specified distance, though lower intensities (750-2,500 lux) of blue-enriched light can be equally effective 1, 3, 5
• Fluorescent lamps with emission spectrum between 400-450 nm are also used, particularly for certain dermatologic applications 1

Distance and Positioning

• Position the light box 30-34 inches (approximately 1 meter) from the patient's face 1, 2, 3
• The light should be at or slightly above eye level, angled downward toward the eyes 1
• Patients do not need to stare directly at the light continuously but should keep their eyes open with intermittent glances toward the light source 4, 6

Treatment Parameters

Timing and Duration

• Administer light therapy in the morning hours, typically between 09:00-11:00 AM for most circadian rhythm disorders and seasonal affective disorder 1, 3
• Standard treatment duration is 30-60 minutes per session at 10,000 lux 1, 4, 6
• For lower intensity blue-enriched light (750 lux), 30 minutes may be sufficient 5
• Treatment should occur daily, typically 5-7 days per week 1

Light Intensity Specifications

• Standard bright light therapy: 10,000 lux for 30 minutes 4, 7, 6
• Alternative: 2,500-5,000 lux for 1-2 hours (particularly for elderly patients with dementia) 1, 3
• Blue-enriched white light: as low as 750 lux for 30 minutes can be equally effective 5
• Irradiance should be at least 30 μW/cm²/nm in term infants for neonatal phototherapy 1

Safety Precautions and Monitoring

Pre-Treatment Screening

• Patients with pre-existing retinal diseases or other eye conditions should undergo ophthalmologic consultation before starting light therapy 2, 4
• Screen for history of migraine, as light therapy triggers migraines in approximately one-third of susceptible individuals 2
• Review medications for photosensitizing drugs, which require periodic ophthalmologic monitoring during treatment 4

Common Side Effects

• Monitor for headaches, eyestrain, nausea, agitation, and eye/vision problems, which occur in approximately 45% of patients but are typically mild and transient 2, 7
• These side effects usually appear early in treatment and resolve spontaneously without requiring treatment discontinuation 7
• Long-term use (3-6 years with cumulative exposure of 60-1,250 hours) has not been associated with ocular abnormalities 4

Special Populations

Elderly Patients with Dementia

• Implement bright light therapy at 2,500-5,000 lux for 1-2 hours daily between 09:00-11:00 AM 3
• Position the light source approximately 1 meter from the patient 1, 3
• Use white broad-spectrum light boxes or tabletop devices 1
• Treatment duration of 4-10 weeks is typically needed to see improvements in sleep consolidation and behavioral symptoms 1, 3

Circadian Rhythm Disorders

• For delayed sleep-wake phase disorder, administer light therapy immediately upon awakening in the morning 1
• For advanced sleep-wake phase disorder, evening light exposure may be more appropriate 1
• Combine with strategic avoidance of bright light during evening hours to maximize circadian phase-shifting effects 1

Treatment Environment

• Patients can engage in other activities during light therapy sessions (reading, eating breakfast, working) as long as they remain within the specified distance and maintain intermittent visual exposure to the light 4, 6
• The treatment can be administered at home with portable LED devices, making it more practical than hospital-based therapy 1
• Ensure the room has minimal competing bright light sources that could reduce the relative intensity of the therapeutic light 1

Expected Response Timeline

• Initial response typically occurs within 4-6 hours of starting phototherapy for neonatal hyperbilirubinemia 1
• For seasonal affective disorder and circadian rhythm disorders, significant improvement usually appears within 2-4 weeks of daily treatment 1, 8, 5
• Approximately 75% of patients with seasonal affective disorder achieve clinical remission with appropriate light therapy 4