Seasonal Depression

Seasonal Effective Disorder . . . Also called: SED or SAD, Seasonal depression, Seasonal mood disorder

Some people experience a serious mood change when the seasons change. They may sleep too much, have little energy, and crave sweets and starchy foods. They may also feel depressed. Though symptoms can be severe, they usually clear up. This condition is seasonal affective disorder (SAD).

SAD is a type of seasonal depression, usually occurring in the winter, and effecting millions of people between September and April with the peak depression occurring in the winter months of December, January and February. SAD is a seriously disabling illness, preventing people from functioning normally. Also, millions of others suffer from a milder version called "subsyndromal SAD" or "winter blues," less disabling but still impairing and uncomfortable. A less common type of SAD happens in the summer months usually in very hot climates, such as Arizona.

What causes SED? Some experts think it's a lack of sunlight during winter, when the days are shorter. In the United States, it is much more common in northern states. Light therapy, in which patients expose themselves to a special type of light for 30-minutes every day often helps. Other treatments include:

• Medicines
• Changes in diet
• Learning to manage stress
• Going to a sunny climate during the cold months

Most Seasonal Effective Disorder (SED) symptoms stem from daily body rhythms that have gone out-of-sync with the sun, a NIMH-funded study has found. The researchers propose that most patients will respond best to a low dose of the light-sensitive hormone melatonin in the afternoon in addition to bright light in the morning. Rhythms that have lost their bearings due to winter's late dawn and early dusk accounted for 65 percent of SAD symptoms; re-aligning them explained 35 percent of melatonin's antidepressant effect in patients with delayed rhythms, the most common form of SAD.

SAD affects many people in northern latitudes in winter, especially young women, and is usually treated with bright light in the morning. The pineal gland, located in the middle of the brain, responds to darkness by secreting melatonin, which re-sets the brain's central clock and helps the light/dark cycle re-set the sleep/wake cycle and other daily rhythms. Researchers have pinpointed how rhythms go astray in SAD and how they can be re-set by taking melatonin supplements at the right time of day. The findings strengthen the case for daily rhythm mismatches as the cause of SAD.

Researchers tracked sleep, activity levels, melatonin rhythms and depression symptoms of 68 SAD patients who took either low doses of melatonin or a placebo in the morning or afternoon for a winter month when they were most symptomatic. They had determined from healthy subjects that a person's rhythms are synchronized when the interval between the time the pineal gland begins secreting melatonin and the middle of sleep is about 6 hours.

Seventy-one percent of the SED (SAD) patients had intervals shorter than 6 hours, indicating that their rhythms were delayed due to the later winter dawn. Taking melatonin capsules in the afternoon lengthened their intervals, bringing their rhythms back toward normal. The closer their intervals approached the ideal 6 hours, the more their mood improved on depression rating scales, supporting the hypothesized link between out-of-sync rhythms and SAD.

"SAD may be the first psychiatric disorder in which a physiological marker correlates with symptom severity before, and in the course of treatment in the same patients, referring to patients' rhythm shifts towards the 6 hour interval in response to melatonin.

Taking melatonin at the correct time of day which is afternoon for patients with short intervals and morning for the 29 percent of patients with long intervals have more than doubled their improvement in depression scores, compared to taking a placebo or the hormone at the incorrect time. While the study was not designed to test the efficacy of melatonin treatment, the researchers suggest that its clinical benefit "appears to be substantial, although not as robust as light treatment." They propose that the 6-hour interval index may be useful for analyzing the circadian components of non-seasonal depression and other sleep and psychiatric disorders.

Symptoms of Seasonal Effective Disorder & Depression:

• Depression that starts in fall or winter
• Increased sleep
• Increased appetite with weight gain
• Unacceptable weight gain
• Carbohydrate cravings
• Fatigue or inability to carry out normal routine
• Feelings of misery, guilt, low self-esteem, despair, apathy
• Lack of energy, slow, sluggish, lethargic movement
• Avoidance of social contacts or exhibiting "hibernation" syndrome
• Increased susceptibility to stress
• Decreased interest in work or other activities
• Mood swings and periods of hypo mania in spring & autumn

Symptoms of Seasonal Depression in children:

• Feeling tired and washed out
• Feeling cranky and irritable
• Temper tantrums in the winter months
• Slipping grades

The outcome is good with continuous treatment, although some people have the disorder throughout their lives.