Introduction

• Seasonal affective disorder (SAD) is a mental health condition in which moods are affected by the level of sunlight to which a person is exposed. SAD affects most people during the winter but can occur at any time or in any environment where access to direct sunlight is limited. According to the National Mental Health Association, as much as 25 percent of the population suffers from seasonal affective disorder. One of the most common ways to fight this disorder is through the use of light therapy lamps.
  
  

Light Therapy Lamps

• Light therapy is usually administered through a light therapy box. This piece of equipment houses a lamp bulb with the ability to mimic bright natural sunlight. Treatment is done by being exposed to the light box for a certain period of time each day to help lessen the symptoms of seasonal affective disorder. The actual time spent in front of the light box will vary depending on how serious the disorder is and your doctor's recommendations. Treatments can last anywhere from 15 minutes to one hour for two or three times each day. Light boxes range in cost from $300 to $500, but most insurance companies will cover the cost of a light therapy box as long as you have a prescription from your doctor for it.
  
  

Circadian Rhythms

• One way that light therapy works is by targeting the circadian rhythms of the body. Circadian rhythms are the way that your body decides when it will sleep and when it will be awake. Your particular circadian rhythms are largely determined by sunlight. Since during the wintertime the hours of daylight are significantly decreased, circadian rhythms can get thrown off leading to a lack of sleep and feelings of depression. Light therapy works to help reset those circadian rhythms by creating similar light exposure as you would experience during the summer months.
  
  

Melatonin

• The light box also helps reduce the amount of melatonin being created in the body. Melatonin is a hormone secreted from the pineal gland that stimulates the body's sleep cycle. Exposure to the light therapy lamp rapidly decreases the amount of melatonin circulating in the blood. This helps ward of the sleepiness felt by many SAD sufferers and helps to increase energy as well. The reduction of melatonin may also work to improve mood.
  
  

Time

• Since different areas of the world experience varying amounts of light loss during the fall and winter months, the time it takes for a light box to take effect can vary. Some patient's may only need 15 minutes in front of the light box to feel its effects. Others may need a greater period of time at multiple increments during the day to benefit from the light box. How severe your individual body reacts to the loss of light may also affect how long it will take before you see relief from your season affective disorder.