SAD (Seasonal Affective Disorder)

Seasonal affective disorder (SAD), also called winter depression or blues, is a mood disorder where people exhibit depressive symptoms at particular season each year. The disorder is most common in winter season and northern latitudes. More than 10% of people suffer from SAD and about 75% of them are women.

According to the World Health Organization (WHO), depression is a common mental disorder that affects an estimated 350 million people globally. It is also the leading cause of disability worldwide. Those affected by depression suffer greatly and can have a poor quality of life as their ability to function at work, school and within their family is negatively affected. Depression can lead to suicide, which is the second leading cause of death in those between the ages of 15 to 29.


Seasonal affective disorder, or SAD, is perhaps the best known mental illness related to a disrupted circadian rhythm.

The lack of high-quality light disrupts the production of the hormone melatonin in the suprachiasmatic nucleus of the brain. This leaves people with irregular levels of the hormone which produces fatigue, depression and a wide range of symptoms. New studies are suggesting that disrupted circadian rhythms may contribute to a diverse range of mental illness from clinical depression to bipolar disorder.

Seasonal affective disorder, or SAD, is perhaps the best known mental illness related to a disrupted circadian rhythm.



Light Therapy

The symptoms of SAD are thought to be related to the lack of exposure to full-spectrum natural light in the winter months. Medications is shown to be be effective in treating depression in only 60% of the cases. New research reveals that light therapy is highly effective, even more so than Prozac, in treating non-seasonal major depression. 

Light therapy for depression has been studied as early as in the 1970s. It has been proven as effective as an antidepressant as it is thought to restore proper melatonin secretion and synthesis by the pineal gland, which allows re-establishment of the normal rhythm of hormone secretions that occurs daily in relation to a properly functioning circadian rhythm.

Light therapy is inexpensive, easily accessible and has few side effects. Patients can easily use light therapy in combination with other treatments such as psychotherapy and antidepressants and with increasing the melatonin level by wearing virtual darkness glasses or tested and effective blue blockers like Circadian Eyewear.




Light therapy is inexpensive, easily accessible and has few side effects. 




The main therapy for SAD is exposure to extremely bright full spectrum lights everyday at least for 30 minutes the first thing in the morning. This will ensure the production of serotonin, also called the good mood hormone. Serotonin is the base substance for melatonin.

The other part of this equation is managing regular sleep patterns with recommended amount of sleep and harmonizing the master clock with the natural environment. This is possible with virtual darkness therapy and Circadian Eyewear. According to recent studies our ancestors slept much longer hours in the winter than in the summer. 

Wearing the Circadian Eyewear 2-3 hours before sleep and getting the recommended sleep per night with consistency, will ensure the production/secretion of natural melatonin on a timely manner. The balance cycle of light/dark or day/night is what is most important.

Circadian Eyewear Collection




Research from PubMed
Links between Circadian Rhythms and Psychiatric Disease.

Differential association of circadian genes with mood disorders: CRY1 and NPAS2 are associated with unipolar major depression and CLOCK and VIP with bipolar disorder.

Clock Genes and Altered Sleep–Wake Rhythms: Their Role in the Development of Psychiatric Disorders

Testing the role of circadian genes in conferring risk for psychiatric disorders.

Research from Chronobiology
Seasonal Affective Disorder: The Latest Research on Beating the Winter Blues

Mental Illness Associated With Disrupted Circadian Rhythms.

Seasonal Affective Disorder: Sunlight and Your Circadian Rhythm

Melatonin and Myopia: How Sleep Patterns Are Linked to Short-Sightedness.

Research from University of British Columbia
Light therapy effective for depression: UBC study

Research Sources