With falling temperatures comes a rise in Seasonal Affective Disorder (SAD) and the depression that is its hallmark. While feeling down in the dumps is normal and perfectly healthy in response to bad news or serious life challenges, this emotional disturbance is apparently keyed to sunlight.

SAD is not a distinct medical disorder. It is a form a clinical depression that follows a seasonal pattern for at least two years.

The classic symptoms of SAD include:

• Sadness
• Gloomy outlook every day
• Feeling hopeless, worthless, and irritable
• Loss of interest or pleasure in formerly enjoyable activities
• Withdrawal and isolation from family and friends
• Constant lack of energy
• Difficulty sleeping or oversleeping
• Trouble with focus and performance at home and work
• Carbohydrate cravings and weight gain
• Thoughts of death or suicide

Women, youth, those already diagnosed with depression or bipolar disorder, and people who live far away from the equator are at the highest risk of suffering from SAD, especially if depression runs in the family. Compare the 1 percent of SAD patients who live in Florida to the 9 percent who live in the more northerly latitudes of New England or Alaska.

Unlike other forms of depression, SAD symptoms typically start as the days grow shorter in late fall and early winter and last until the following spring. The medical condition can be debilitating and if you think you have it, expert help is advised.

During the winter months, seasonal affective disorder is characterized by:

• Having low energy
• Hypersomnia
• Overeating
• Weight gain
• Craving for carbohydrates
• Social withdrawal (feel like “hibernating”)

The more rare summer SAD presents with:

• Poor appetite with associated weight loss
• Insomnia
• Agitation
• Restlessness
• Anxiety
• Episodes of violent behavior

A common treatment after a diagnosis of SAD is sunshine replacement therapy. Each morning, the patient sits in front of a box equipped with white fluorescent bulbs that emit artificial sunshine and “bathes” in the visible radiant energy. Supplemental treatment from talk therapy and antidepressant drugs may be recommended for those who don’t respond to increased light levels alone.

SAD is more than merely a psychological reaction to shorter days and longer nights. Less natural sunlight is known to cause dips in serotonin, the neurotransmitter that monitors mood. The body’s circadian rhythms (our internal clock) becomes upset and interferes with sleep-wake cycles.

There seems to be a link between elevated serotonin levels in people suffering from SAD:

“One study found that people with SAD have 5 percent more serotonin transporter protein in winter months than summer months. Higher serotonin transporter protein leaves less serotonin available at the synapse because the function of the transporter is to recycle neurotransmitter back into the pre-synaptic neuron.”

Light deprivation can also ramp up melatonin levels, a hormone linked to sleep and mood which the body secretes in greater amounts after the darkness falls outside. Over time, reduced exposure to natural light can also create a vitamin D deficiency which is associated with serotonin activity, producing fatigue, bone and back pain, depression, wounds that heal slowly, bone and hair loss, and muscle pain.

While regular dosing with the right amount of extra light can relieve the symptoms of SAD, overdoing it can create problems, too, including feeling nervous, agitated, and prone to headaches.

SAD can sour relationships with other people and make getting along with others difficult. People with mood problems may discover that other things in their lives also start to fall apart. They may find less enjoyment from life, work performance may decline, and relationship difficulties may become troublesome.

A person who suspects s/he has SAD should talk things over with a professional healthcare provider to rule out a vitamin D deficiency or other possible cause for constantly feeling blue. The most important question asked is:

“Do your symptoms interfere with your function at home, work and/or relationships?”

A yes answer may prompt fast action. In addition to daily light-box exposure, people with SAD should seize every opportunity to go out into real sunshine whenever the sun is above the horizon. Developing an interest in outdoor winter activities such as snowshoeing, skiing or ice skating can be quite helpful.

Regular exercise – 20-30 minutes four or five times a week – helps to balance the body’s hormones and can be very useful in combatting SAD. Experts call exercise a natural antidepressant capable of raising serotonin and endorphin levels, both of which influence mood.

Cognitive-behavioral therapy (also called cognitive therapy or CBT) can also be useful in treating SAD. This active, structured form of psychotherapy revolves around the idea that a person’s world view has a major influence on emotions and behavior:

“Cognitions (thoughts or mental pictures) are based on beliefs and assumptions developed from previous experiences. Dysfunctional cognitions often lead to unpleasant feelings and problematic behavior.”

CBT seeks to consciously connect automatic thoughts, emotions, and behavior, substituting more rational and adaptive ideas for negative, dysfunctional beliefs. Patients learn new ways to cope with stressful triggers.