Seasonal affective disorder, also known as winter depression, is an affective, or mood, disorder. Most SAD sufferers experience normal mental health throughout most of the year, but experience depressive symptoms in the winter or summer. The condition in the summer is often referred to as Reverse Seasonal Affective Disorder.
Seasonal mood variations are believed to be related to light. SAD is measurably present at latitudes in the Arctic region, such as Finland (64Âº 00Â´N) where the rate of SAD is 9.5%. Cloud cover may contribute to the negative effects of SAD. SAD can be a serious disorder and may require hospitalization. There is also potential risk of suicide in some patients experiencing SAD. One study reports 6-35% of sufferers required hospitalization during one period of illness. The symptoms of SAD mimic those of dysthymia or clinical depression. At times, patients may not feel depressed, but rather lack energy to perform everyday activities. Norman Rosenthal, a pioneer in SAD research, has estimated that the prevalence of SAD in the adult U.S. population is between about 1.5% (in Florida) and about 9% (in the northern US).
One possibility is that SAD is related to a lack of serotonin, and serotonin polymorphisms could play a role in SAD.
Another theory is that melatonin produced in the pineal gland is the primary cause since there are direct connections between the retina and the pineal gland. Mice incapable of synthesizing melatonin appear to express â€œdepression-likeâ€ behaviors, melatonin receptor ligands produce an antidepressant-like effect.
Subsyndromal Seasonal Affective Disorder is a milder form of SAD experienced by an estimated 14.3% vs. 6.4% of the U.S. population. The blue feelings experienced by both SAD and SSAD sufferers can usually be dampened or extinguished by exercise and increased outdoor activity, particularly on sunny days, resulting in increased solar exposure.
Connections between human mood, as well as energy levels, and the seasons are well-documented, even in healthy individuals. Particularly in high latitudes (50Â°N or S) it is common for people to experience lower energy levels.
There are many different treatments for seasonal affective disorder, including light therapies, medication, and ionized-air reception. Bright light treatments are common, however as many as 19% of patients stop use because of the inconvenience. Specially designed light, many times brighter than normal office lighting, is placed near the sufferer. Most treatments use 30-60 minute treatments, however this varies depending on the situation.
Patients using light therapy can experience improvement during the first week, but increased results are evident when continued throughout several weeks.