Light Therapy An Effective Treatment for Seasonal Affective Disorder (SAD)
Light therapy has been shown to be as effective as the antidepressant fluoxetine (Prozac) in combating seasonal depression or Seasonal Affective Disorder (SAD). Bright light therapy was shown to improve mood as well as conventional antidepressant medications, in a new, carefully designed randomized controlled trial lead by Dr. Ritsaert Lieverse, a psychiatrist at the VU University Medical Center in Amsterdam, whose theory is that bright light therapy elevates mood by activating the brain’s so-called circadian pacemaker, a structure called the suprachiasmatic nucleus. Dr. Lieverse says that bright light therapy may also work by targeting depression-associated neurotransmitter systems that regulate serotonin and dopamine.
Earlier studies have also confirmed the effectiveness of bright light therapy. In a 2005 meta-analysis of randomized, controlled trials of light therapy, the American Psychiatric Association Committee on Research in Psychiatric Treatments found the results “[suggestive] that bright light treatment [and dawn simulation for SAD and bright light for nonseasonal depression] are efficacious, with effect sizes equivalent to those in most antidepressant pharmacotherapy trials.” After proving effective in SAD patients, light treatment is moving beyond SAD to treat nonseasonal depression (unipolar, bipolar, and major depressive disorder), premenstrual dysphoric disorder (PMDD), post partum depression, adult ADD, bulimia nervosa, circadian sleep phase disorders, and more.
What is Seasonal Affective Disorder (SAD)?
SAD is a condition of depression and fatigue that occurs in winter months when days are shorter and exposure to sunlight is limited. The reduced sunlight during these months causes the body to fall out of its natural circadian rhythm, which plays a major role in mood. People with the disorder may feel drained, depressed, lack interest in normal activity, among other symptoms. Patients that experience SAD may be more prone to slowing down in the winter, akin to hibernation. Research has explained that retinal sensitivities cause an inability to absorb adequate sunlight in SAD patients. According to researchers at Laval Univerity in Canada, SAD patients were reported to have lower rod retinal sensitivity and lower cone maximal amplitude. So it makes sense that administering more light to these patients in darker months could alleviate the underlying disorder.
How to Use Bright Light Therapy
Studies show that shorter, higher intensity sessions in the morning are the most effective course of treatment. The greater the amount of lux (a measure of light intensity) the less treatment time needed. 10,000 lux of white light for 30 minutes in the morning is ideal (2,500 lux in 2 hour sessions produced remission rates of approx 53% while 10,000 lux in 30-40 min sessions produced remission rates of approx 75%). Morning exposure works by halting the secretion of melatonin and combating fatigue upon waking. Light treatment should begin no later than 8.5 hours after the onset of melatonin (sleep). Studies have shown that light therapy given 7.5–9.5 hours after melatonin onset yields twice the remission rate (80% versus 38%) of light given 9.5–11.0 hours after melatonin.
Regulating the body’s sleep cycle and circadian rhythm is crucial in combating SAD. Go to bed and rise at the same time each day. Since blue light blocks melatonin production avoid light emitting electronics in the evening, such as from TVs, laptops, ipads, and blackberries. If evening electronics are necessary, use a blue light filter on the screen. If sleep aids are necessary, take natural forms such as chamomile tea and melatonin. Melatonin can help you sleep deeper and lengthen the sleep cycle.
For assistance waking, try a light box or dawn simulator that gradually simulates the sun rise over a period of 60-90 minutes starting from 0.001 lux (“starlight”) when the patient is still sleeping to approximately 300 lux (equivalent to “sunrise under tree cover”) when the patient is scheduled to rise. The basic therapeutic strategy is to set time of the sunrise signal earlier than outdoors in winter. Dawn simulation can be done cheaply with no side effects with a regular bedside lamp by hooking up a timer and rheostat to the lamp. In addition to stimulating the gradual shut down of melatonin production, dawn simulation (ie. simulating sunrise at 6am in December) could trick the brain into thinking it is summer and thus get the body out of its hibernation mode.
Adhering to a light exposure schedule can help regulate the body’s circadian rhythm. Patients who have problems waking up in the morning should initially schedule their light exposure at their usual wake up time however as treatment progresses and depression and fatigue dissipate, the wake up time can be edged up over time towards an earlier target wake up. Patients may be comfortable with less sleep overall once the antidepressant effect has set in.
When to start treatment
If a patient is aware of their susceptibility to SAD, it would make sense to start light therapy when the shorter days and colder weather start limiting their sunlight exposure. Patients should pay attention to early warning signs such as difficulty waking, daytime fatigue, and carbohydrate cravings and begin treatment once they occur.
Light Boxes We Like
Day-light Sky – $149.92
This desk lamp can be used at the office or home. Features 10,000 LUX of balanced white light and a glare-free diffuser that filters 99.3% of UV rays.
Philips Hf3318/60 Energylight – $219.99
Verilux HappyLight 4500 Sunshine Supplement Light System – $67.88
A patented Verilux 4,500 lux bulb that does not emit harmful UV rays or EMFs. This model was recommended on the Dr. Oz show. Comes with a 3 year warranty.
Philips Hf3485 Wake-up Light Plus – $159.99
Other Treatments for SAD
Other methods that combat the fatigue and depression associated with SAD include cognitive behavioral therapy (CBT), vitamin D supplementation, fresh air, and regular exercise. Two recent studies show that daily aerobic exercise for 60 minutes is as effective as bright light therapy for patients with SAD, while those with nonseasonal depression responded selectively. Fresh air is not to be dismissed as a course of treatment.
Recently, the antidepressant effect of high-density negative air ions has been observed in patients with chronic depression. Negative ion emitting devices may be ineffective and emit unsafe levels of ozone, so patients can promote their exposure by spending more time where negative air ions are higher naturally – in humid, vegetated environments and at the seashore. Negative air ions are lower in urban environments and heated or air conditioned interiors.
Access to green space within a kilometre of one’s residence has been reportedly associated with improved mental health. Large population studies show that those with the least green space within one kilometre of home have a 25% greater risk of depression and a 30% higher risk of an anxiety disorder.
Risks and Safety Concerns
Safe light boxes contain a plastic diffuser screen which minimize or eliminate eyestrain and damage by filtering out most harmful UV rays. Blue light can be very harmful, causing macular degeneration, a leading cause of blindness. Do not use blue light boxes, as white light is both safe and effective. A factor that compromises the efficacy of light therapy treatment is the presence of certain disorders such as anxiety disorders and personality disorders.
Light therapy rarely has side effects but has in some cases has induced a state of hypomania or mania. Bipolar patients in particular should avoid blue light or prolonged bright light exposure. Because of the risks of mania and even suicide, do not attempt light treatment on your own. Make sure to conduct this therapy with a physician as part of a treatment plan that also incorporates careful monitoring of blood serum levels of other causes of fatigue such as low vitamin D, iron, and hypothyroidism.
Image Credit: Holistic Mental Health Albany
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