Besides ushering in cooler temperatures and holiday cheer, the months of December, January and February are peak times for Seasonal Affective Disorder (SAD), according to the Alabama Department of Mental Health in Montgomery.

SAD is a mood disorder associated with depression and related to seasonal variations in light. It affects nearly half a million people, usually between September and April.

Depression is usually mild to moderate but can be severe. SAD can be diagnosed after three consecutive winters of symptoms if they are also followed by complete remission in the spring and summer months.

According to Mental Health America, symptoms include depression, anxiety, overeating, lethargy and social withdrawal.

SAD tends to affect women more, as three out of four sufferers are women. The main onset appears anywhere between the ages of 18 and 30, but more typically in the early twenties.

According to Dr. Timothy Stone, medical director of the Alabama Department of Mental Health, in northern regions, nearly 14 percent of the population experiences SAD. In more temperate regions like Alabama, 6 percent of the population experiences SAD.

The severity of SAD can be traced to a person’s vulnerability to the disorder, linked to having at least one close relative with a psychiatric condition, usually severe depressive disorder or alcohol abuse.

“SAD can disrupt a person’s life in several ways including affecting work performance by causing impairments in concentration, energy and motivation,” Stone said. “Often people with SAD have an increased need for sleep and have a difficult time getting up in the morning.

“They are more often late to work or do not show up at all. The quality of their work suffers, and they are less efficient and less productive. SAD can also negatively impact close relationships by causing irritability as well as a tendency to pull away from the world and isolate oneself,” he said.

Causes of SAD have been traced to seasonal light variations in humans, as well as levels of melatonin. There are a variety of treatments and treatment levels for those suffering from SAD.

“People with the disorder can increase the amount of time they spend outside to gain some relief,” Stone said. “Using manufactured light-boxes that produce specific wavelengths of light, many of which can be purchased fairly cheaply over the Internet, has been found as effective in treating SAD as psychotherapy or medication. This treatment works best when used daily, in the morning, from October through March.”

Some people often say they have the “winter blues,” which is in fact a milder form of SAD, but the main thing to remember is if depressive symptoms are severe enough to significantly affect one’s daily living, contact a mental health professional.

For more information about SAD, visit the National Alliance on Mental Illness (NAMI) website at www.nami.org or the Mental Health America website at www.nmha.org.