SAD (also known as "seasonal affective disorder," "winter depression," "seasonal depression," or "winter blues") quite simply occurs when the sufferer does not receive sufficient daylight through the eyes to trigger hormone releases in the brain that control the wake cycle within the 24-hour day.
One in eight suffer from this condition in some form (NHS, 2009). Symptoms may include lack of motivation, cravings for carbohydrates, sleep disruptions, headaches and depression.
Circadian rhythm disorders due to jet lag, shift work sleep disorder (SWSD), insomnia and listlessness due to working in factories and offices have also been attributed to issues with daylight.
How Much Light Therapy?
To counter SAD, sufficient brightness and duration of light is required to trigger the release of certain hormones. Brightness is measured in “lux.” The following might help give some frame of reference to what lux means:
- 100,000lux: equivalent to a bright summer’s day
- 10,000lux: a bright spring morning soon after sunrise
- 500 – 1000lux: a bright office
- 300 – 500lux: domestic lighting
Blue Light Therapy
But it’s not just the brightness that is important; the Kelvin, or the colour of the light, is crucial. High Kelvin or short wavelength is bias towards the blue spectrum; low Kelvin or long wavelength is bias towards the red or yellow spectrum, as can be appreciated from the following:
- 28,000k: blue sky
- 5600k: the appearance of ordinary daylight
- 1800k: firelight
- 700k: red glow
What Does Bluewave Technology Mean?
Natural daylight, being predominantly white, contains all the colours of the spectrum, but research conducted through the Moorfields Eye Hospital has specified that light in the short wavelength, or blue spectrum activates special cells in the back of the eye that triggers the production of the mood lifting hormone seratonin and blocks the sleep hormone melatonin. Light in the short wavelength would seem to be most effective for SAD.
Light boxes that contain bluewave technology provide light in this specific spectrum. Being more effective, less brightness is required than the traditional 10000lux white light of some conventional light boxes. For this reason, light boxes with bluewave technology require a mere 2,500lux and less treatment time, and are therefore more efficient. Furthermore, a special diffuser screen blocks out harmful UV rays, so the user may benefit from the blue light.
Treatment for SAD
When to use the light box is more important than how much. Research has shown that using light therapy for one to two hours per day early in the morning is more effective than using it at any other time. Light boxes that provide bluewave technology require only half an hour or so. Gradual increase in brightness simulating a natural sunrise has also shown to be more effective for SAD than brightness that occurs rapidly. SAD alarm clocks in the form of dawn simulators provide this effect.
Which Light Boxes
The Litebook Elite and SAD Litepod are compact and portable, but the Apollo Golite M2, Golite P1 and Golite Blu have added bluewave technology. SAD alarm clocks and dawn simulators that light up gradually are also available. Some have the added features of natural sound effects or music if desired.
Cheap Light Boxes
Since SAD is considered to be a medical condition, the sufferer may be exempt to paying VAT on the price of the SAD lamp. A VAT exemption self-declaration form may be required.
The Best Light Box for SAD
Light therapy has been shown to provide an effective treatment for SAD, helping to trigger the mood enhancing hormone seratonin and suppressing the sleep hormone melatonin. Although the conventional 10000lux white light therapy will effectively treat SAD, light boxes with bluewave technology require a mere 2,500lux to target the causes of SAD. Early morning dawn simulation is the most effective light therapy for SAD.
Note: Although light therapy is a safe treatment, consultation with a GP or eye specialist is recommended prior to embarking upon light therapy.
References and Links:
“Seasonal Affective Disorder” (National Health Service, 2008)
“A Controlled Study of Dawn Simulation in Subsyndromal Winter Depression”
(Department of Psychiatry and Behavioural Sciences, University of Washington, 1993)
“Brain Chemistry Winter Blues Link” (BBC, Sep 2008)
“Ten Things You Need to Know About Sleep” (BBC, 2007)
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