Humankind evolved under the outdoor day–night cycle, and it is essential to maintaining normal, healthy physiology. The importance of light – beyond vision– has been known in all cultures for all time. The scientific research effort, however, is recent. It was inspired by findings that light exposure directly affects hormone levels and can reset the body clock either forward or backward. Expert professional consensus recommends using diffuse white light that blocks out ultraviolet radiation (in contrast to the “sun lamps” used for tanning, which are dangerous both to skin and eyes).
Scientists think that light therapy works at several different levels, producing a combined beneficial effect. It is directly energizing for most people, thus combating mood–associated fatigue. When used at an appropriate morning hour (or in rare cases, evening hour), it corrects the misalignment of the internal body clock with external night and day. Finally, it stimulates the brain’s production of neurochemicals that are thought to be antidepressant (and in that sense, it mimics drug effects in a more natural way, without the need for drugs).
- For light therapy sessions
- By adjusting the angle of the lamp, your Day–Light makes a versatile task lamp
- For pleasant ambient lighting
- You may prefer the two–light setting for less intensity in small spaces.
Although researchers don’t have firm numbers, lots of people are light deprived. Symptoms of light deprivation include:
- Feeling depressed or moody during the fall and winter.
- Fatigue, lack of energy, and difficulty getting up in the morning.
- Problems getting things done (lack of motivation).
- Reduced social contact (often reduced sexual interest).
- Cravings for carbohydrate and weight gain.
Treatment regimens should be individualized and always with doctor’s supervision in cases of full–blown clinical depression. Light therapy involves daily, scheduled exposure to intense levels of artificial light in order to regulate seasonal mood swings, improve sleeping patterns, and produce a general sense of well–being.
According to medical researchers, the fluorescent light box is the preferred device for light therapy, with a recommended starting dose of 10,000 lux for 30 minutes per day. (Lux is the unit of measuring the illumination intensity of light.) The required parameters for 10,000 lux light therapy have been thoroughly clinically tested at major university centers, and have been established as the international standard for treatment of winter depression, milder “winter doldrums,” and other chronobiological, circadian rhythm sleep and mood disturbances.
The general regimen consists of 30–minute early–morning exposure sessions, during which the user sits at a distance of 12 inches (30.5 cm) from the screen, and concentrates on the tabletop work surface – for reading, writing, laptop, breakfast, and so on. Many people find it convenient to get their light therapy session during breakfast, before leaving the house. However, the optimum timing and duration of the light therapy session for individuals differs between people, and therefore you will need to explore a bit to find what works best for you.
The light level can also be switched down when the user wants longer exposures during the day. The flexible angular tilt allows the fixture to be used as an exceptionally powerful task or reading lamp, or for pleasant ambient lighting at a distance. One of the unique features is the screen–height adjuster, allowing optimum positioning according to the user’s height relative to the height of the table and chair. The unit features a smoothly diffused polycarbonate screen that maximally filters out ultraviolet (UV) radiation – an important safety precaution. Spectral emission properties have been independently verified by laboratory calibrations at Columbia University.
When used correctly, the Therapeutic light is an efficient way to help alleviate the fatigue, blues and other symptoms you may experience during the shorter days of the year. You should use the three-light setting 10,000 lux intensity. (The one–light setting delivers 5,000 lux.) Begin with 30 minutes at 10,000 lux in the early morning.
Remember: as long as you use a light therapy device designed according to the specifications recommended by light therapy experts, there is little risk of adverse side effects, and you can safely modify and monitor your progress.
The Center for Environmental Therapeutics (CET) has set standards for light box design that consumers, doctors and insurance companies should keep in mind. This light was designed with these standards in mind.
CET Standards for Light Box Design
- Only light boxes should be used for bright light therapy. Visors have not yet been shown effective in placebo-controlled studies.
- The light box should provide 10,000 lux of illumination at a comfortable sitting distance (with the eyes 12 inches or more from the center of the screen).
- The lamps should give off white light rather than colored light. (Extended exposure to blue light may be harmful to the eyes, and red light is not effective for light therapy.)
- Fluorescent lamps should have a filter that blocks ultraviolet (UV) rays. UV rays are harmful to the eyes and skin.
- The light source should be covered with a smooth diffusing screen that evens the delivery of light. Bare bulbs and sharp points of light (including LED displays) can produce intolerable glare, forcing your gaze out of the therapeutic field.
- Color temperature of lamps should be in the 3000–5000 Kelvin range for comfortable usage.
- Light boxes should be equipped with high-efficiency ballasts that operate at 20,000 cycles per second in order to avoid flicker that can cause headaches. (Inferior magnetic ballasts operate at only 60 cycles per second.)
- The light should be projected downward toward the eyes at an angle to minimize aversive visual glare.
- The screen area should be at least 190 square inches (for example 12 inches high by 16 inches long) to provide a satisfactory field of illumination. (When using a compact light box, even small head movements will take the eyes out of the therapeutic range of light.)
Concerns have been voiced about the blue light wavelengths emitted from white light boxes, as there is some evidence that chronic exposure to blue light can damage the retina.1 However, the cells in the eye that transmit light information to regulate circadian rhythms are responsive specifically to the blue component of sunlight – this means that some blue wavelengths are important for light therapy to be effective.2, 3 To minimize the potential for blue light damage, the Center for Environmental Therapeutics recommends therapeutic light boxes with relatively less blue – those with color temperatures in the range of 3000-4000 degrees Kelvin, rather than 5000 or higher. The Day-Light has a color temperature of 4000 degrees Kelvin, therefore meeting the CET’s recommendations for minimizing blue light exposure.
Some light boxes use only green light to avoid exposure to blue wavelengths, however green light alone has not been adequately tested in peer-reviewed studies for its efficacy in treating seasonal depression. In fact, there is evidence that effective light therapy should include both blue and green wavelengths (white light) for optimal results.4 Other light boxes use blue-enriched white light, which is no more effective than standard white light but has a much higher color temperature, carrying the risk of retina damage.5, 6 The Day-Light has been selected by Dr. Fuhrman as the best product for the combination of efficacy and safety – it is designed to provide therapeutic benefit with minimal blue light exposure.
Those with age-related macular degeneration (AMD) or those who have a family history of AMD should consult a physician before using the Day-Light.
Light therapy should not be used with certain photosensitizing medications, including some antipsychotic, antidepressant, psoralen, antiarrhythmic, antimalarial, antirheumatic, porphyrin, tetracycline, diuretic, and sulfonamide drugs, and St. John’s Wort.7 If you are taking any medications, consult your physician before using the Day-Light.
1. Algvere PV, Marshall J, Seregard S. Age-related maculopathy and the impact of blue light hazard. Acta Ophthalmol Scand 2006;84:4-15.
2. Brainard GC, Hanifin JP, Greeson JM, et al. Action spectrum for melatonin regulation in humans: evidence for a novel circadian photoreceptor. J Neurosci 2001;21:6405-6412.
3. Thapan K, Arendt J, Skene DJ. An action spectrum for melatonin suppression: evidence for a novel non-rod, non-cone photoreceptor system in humans. J Physiol 2001;535:261-267.
4. Gooley JJ, Rajaratnam SM, Brainard GC, et al. Spectral responses of the human circadian system depend on the irradiance and duration of exposure to light. Sci Transl Med 2010;2:31ra33.
5. Gordijn MC, t Mannetje D, Meesters Y. The effects of blue-enriched light treatment compared to standard light treatment in Seasonal Affective Disorder. J Affect Disord 2012;136:72-80.
6. Meesters Y, Dekker V, Schlangen LJ, et al. Low-intensity blue-enriched white light (750 lux) and standard bright light (10,000 lux) are equally effective in treating SAD. A randomized controlled study. BMC Psychiatry 2011;11:17.
7. Center for Environmental Therapeutics: Bright Light Exposure Risks [http://www.cet.org/eng/Therapy_ExposureRisks_ENG.html]