Light Exposure, Seasonal Changes, SAD, Seasonal Affective Disorder

The human body clock regulates not only daily rhythms such as sleeping and waking, but also seasonal changes in physiology. Humans that live in temperate zones where the climate changes with the seasons exhibit seasonal changes in behavior and activity just as other mammals do.  The normal response of mammals to the changing seasons is to alter their activities and behaviors with respect to eating, sleeping, socialization, and sexual activity.

It is the changing day length that signals the changes of the seasons to the internal body clock. In all mammals, including humans, information regarding the day length reaches the brain by way of a neural pathway from the eye to the biological clock in the brain.  In winter, the shorter days cause changes in the body's metabolism that can result in mood changes.  

When seasonal changes of mood are severe, this condition is known as Seasonal Affective Disorder (SAD) or seasonal depression.  Light therapy in winter is used to make the days appear longer. This restores the summer pattern of sleep and metabolic activity, and restores the mood to a summer pattern. 

One function of the body clock is to regulate the production of the hormone melatonin in the pineal gland.  Melatonin has widespread influence on brain activity and is associated with serotonergic pathways, including those which affect mood. New studies suggest that light affects these serotonergic pathways, and light therapy has accordingly been proposed as an potential alternative to drug treatment for many forms of depression.    Click for studies with Lo-LIGHT lamps on the benefits of light therapy for major depression and bipolar depression

Originally it was thought only high intensities of artificial light could realign the body clock in humans.   Recent research confirms that low intensities of the wavelengths provided by a Lo-LIGHT can stimulate the body clock in humans to the same extent as high intensities of white light. 
Click for more information on why low-intensity Lo-LIGHT therapy is as effective as bright light therapy 

Sunnex developed the Lo-LIGHT phototherapy lamp out of a unique patented technology that reproduces the effect of high-intensity light, but eliminates the discomfort and potential hazard to the eyes associated with "Bright Light" therapy. The Sunnex Lo-LIGHT is a convenient, attractive, high-quality alternative to bright light therapy.

Click  for more information on Circadian Rhythms, Light Exposure, and Sleep Disorders