The Importance of Visible Light


Absence of Visible Light May Cause
Seasonal Affective Disorder – SAD

The visible portion of sunlight (without the UV–light) is absolutely necessary for the prevention of Seasonal Affective Disorder (SAD), a form of depression caused by the brain's insufficient production of serotonin and the Pineal Gland's insufficient production of melatonin. The insufficient productions of serotonin and melatonin may lead to depression and/or mood swings.


The retinas of your eyes are part of your brain, and your retinas need to be stimulated with at least 2,500 lumens of full–spectrum lighting for at least 60 minutes every day. You can get this light by indirect sunlight where you work or live, or from a light box (found in hardware stores in the "snow–belt" states), or you may buy one online by simply typing in the search box: "10,000 lux light box." These light boxes are equipped with UV–filters to prevent UV–radiation from reaching your skin and eyes. The best prices are at Amazon.com. Before you purchase a light box, visit: www.skincancer.org/what-to-look-for-in-a-light-box.



Two Types of Seasonal Affective Disorder

There are two seasonal patterns with SAD. One starts in the fall and continues through the winter, while the other starts in late spring or early summer.


Symptoms of "winter" SAD may consist of difficulty waking up in the morning, morning sickness, tendency to oversleep as well as overeat, and especially a craving for carbohydrates, which leads to weight gain. Other symptoms include a lack of energy, difficulty concentrating on completing tasks, and withdrawal from friends, family, and social activities. All of this leads to the depression, pessimistic feelings of hopelessness, and lack of pleasure which characterize a person suffering from this disorder.


Symptoms of "summer" SAD may consist of symptoms of classic depression including insomnia, anxiety, irritability, decreased appetite, weight loss, social withdrawal, and a decreased sex drive. Additionally, many patients are unable to cope with the increased temperatures during spring and summer.


Approximately 6% of adults in the US experience SAD. One study reports about 20% of sufferers required hospitalization during one period of illness. At times, patients may not feel depressed, but rather lack energy to perform everyday activities.


If you feel like you may have mild depression (especially during the winter), you may be suffering from SAD, and may want to discuss this with your mental healthcare provider. Tanning on a tanning bed will not help you since they do not emit a full–spectrum light (like the sun or light box), and even if the bed did, your eyes are shielded during tanning.


You may want to read more about SAD at www.WebMD.com–SAD.