SAD is especially prevalent in countries at the extreme northern and southern latitudes, where there may be only an hour or two of sunlight each day during the winter.
Every fall, like clockwork, Maureen went into an emotional slump. As she sat in my office one December morning, the thirty-eight-year-old bookkeeper and mother of two teenagers said that her body felt heavy and her brain in low gear. Her usually manageable life seemed like too much to handle.
“I can’t get up for work in the morning,” she said. “I jump at the kids, seem to have no patience at all, and my mood is in the dumps.”
Maureen (not her real name) further described feeling sluggish and withdrawn, craving sweet and starchy foods, gaining weight, and sleeping whenever and for as long as she could. These are all symptoms of seasonal affective disorder (SAD), a form of depression that occurs with the decreasing amount of sunlight during the fall and winter. Maureen’s mother and one sister had the same problem, and her recollection of the winters in her childhood home were particularly gloomy, indeed.
Sound familiar? If so, you may also be one of the 10 million Americans with full-blown SAD. More than twice that many people experience less serious versions of the disorder.
What causes SAD?
Traditionally, psychiatrists have labeled this condition the “holiday blues.” The assumption is that this festive time of year brings up gloomy feelings for those who had unhappy childhoods, unfulfilled holidays, or are far away from their loved ones. These influences aside, scientists are now discovering that this condition actually has some biological underpinnings.
An accumulation of evidence confirms that the decreasing sunlight portion of a twenty-four-hour period (called a photoperiod) is the culprit. In people prone to SAD, sunlight deprivation triggers biochemical changes in the brain, directed by the chemicals melatonin and serotonin. This, in turn, results in a disturbance in the natural cycles of the body (called the circadian rhythm) that control sleeping, wakefulness, and hormone secretion. Although everyone has lower brain serotonin levels in fall and winter, people with SAD appear to have a more pronounced problem with serotonin transmission.
Our internal biological clocks are synchronized to the twenty-four-hour light-dark cycle in the physical world. This allows us to be alert by daylight and to become sleepy as the sun begins to set. This pattern worked well for Stone Age people, who could rest and regenerate during the dark night hours. However, the invention of the light bulb (and earlier, the discovery of fire) has led us to run counter to our inborn cycles. No longer living a primal life, we are called upon to function during hours of darkness. In fact, our society is built on this precept—can you imagine the slowdown if in the late fall and winter everyone slept from dusk until daylight?
The melatonin connection
When the eyes transmit light energy along the optic nerve to the pineal gland, a sequence of events is triggered. This tiny, light-sensitive gland at the base of the brain produces the hormone melatonin, which helps regulate inner biological rhythms. The amount of light determines how much melatonin is actually released from the pineal and secreted into the bloodstream.
As light disappears, melatonin release begins and possibly plays a role in triggering sleep and lowering body temperature. As the sun rises, melatonin release is slowed, body temperature rises, and we begin to awaken.
As the nights get longer and more melatonin is present in the blood, the amount of time spent sleeping or feeling sleepy increases, particularly in those vulnerable to SAD. A study published in the July 1994 issue of Arctic Medical Research suggested that elevated daytime blood levels of melatonin may indicate that someone is vulnerable to SAD.
During spring and summer, when the photoperiods are long, melatonin secretion is at its lowest because it’s secreted mainly during the relatively short hours of darkness. The closer we get to winter, the fewer hours of light there are each day and, correspondingly, the longer the period of time each day when melatonin can be released into the blood. Many animals show profound seasonal behavior changes—bears hibernate, birds migrate, salmon return to their birthplace. This process appears to be regulated by melatonin.
Humans also have seasonal rhythms. In many ways, SAD sufferers seem to be in hibernation mode during the cold, dark months, except for their sometimes severe emotional symptoms. Then, once spring and sunlight arrive, they feel energetic and ready to get on with life.
Most people who experience SAD will become melancholy to the point of experiencing real grief at times. Others become more anxious or irritable than usual. The irritability can be so extreme that violence may result. Other symptoms may include fatigue, depression, difficulty concentrating, social withdrawal, increased sensitivity to rejection, reduced activity, increased appetite, and reduced libido.
On a physical level, people suffering from SAD need at least an hour or two more sleep. They also feel a marked decrease in energy, with physical activity of almost any sort seeming to be “just too much.” And they tend to overeat (especially carbohydrates) and gain weight.
Treatment options: Light and supplements
For Maureen and other SAD patients of mine, I have prescribed special lights and St.-John’s-wort. In a short time, Maureen soon found herself coming back to life, “as if spring had come in January.” For the first winter in as long as she could remember, she was able to function just as well as she did the rest of the year.
“I have my life back,” she said. Her family was grateful, too.
The treatment I suggested to Maureen centered around bright light therapy. Effective relief is possible with daily exposure of thirty minutes at a light level of 10,000 lux of high- intensity, artificial light, which is equal to early morning sunlight. (See “Sunlight in a box” to the left.) The treatment also included 900 mg of St.-John’s-wort daily.
Research shows that the herb appears to have a slightly stronger antidepressive effect when combined with light therapy. A study published in a 1994 issue of Journal of Geriatric Psychiatry and Neurology examined twenty patients with significant levels of depression associated with SAD. All the patients took 900 mg of St.-John’s-wort extract (standardized to 0.3 percent hypericin) daily and then received varying levels of light therapy. In four weeks, the group that received bright light (3,000 lux for two hours each day) showed a 72 percent drop in their depression scores, while the group treated with dim light (less than 300 lux) had a drop of 60 percent. Researchers concluded that St.-John’s-wort is almost as effective as light therapy, and with more convenient relief.
My own clinical experience has shown that many people with less severe forms of SAD do quite well on the herb, without the need for the lights.
The B vitamins are also important, particularly B6, for maintaining adequate levels of the neurotransmitters, especially serotonin. In addition, one can take L-tryptophane, 500 to 2,000 mg daily (by prescription from a pharmacy), or 5-HTP (50 to 150 mg daily) to increase serotonin levels.
Though we have no research to prove this, I have had patients use melatonin for SAD. The rationale is that orally administered melatonin shifts the timing of the sleep-wake cycle. So it’s possible that administration of melatonin at just the right time might shift the sleep-wake cycle enough to avoid daytime sleepiness.
Hyla Cass, M.D. is an assistant clinical professor of psychiatry at UCLA School of Medicine and author of St. John’s Wort: Nature’s Blues Buster (Avery, 1998), Kava: Nature’s Answer to Stress, Anxiety, and Insomnia (Prima, 1998), and All About Herbs (Avery, 1999). She has integrated nutritional medicine with psychiatry in her clinical practice, and is a noted public speaker, consultant, and educator on complementary medicine and psychiatry.