Seasonal affective disorder is a pattern of major depressive episodes that occur and remit with changes in seasons. The most recognized form of seasonal affective disorder, "winter depression," is characterized by recurrent episodes of depression, hypersomnia, augmented appetite with carbohydrate craving, and weight gain that begin in the autumn and continue through the winter months. Physicians have many options for treating seasonal affective disorder. While questions regarding the validity of seasonal affective disorder as a syndrome and the mechanism of action of light therapy continue to be investigated, the established effectiveness of light therapy in patients with winter depression supports the usefulness of assessment for this seasonal pattern and consideration of light therapy as an option in addition to existing treatment choices.
What is SAD?
Throughout the centuries, poets have described a sense of sadness, loss and lethargy which can accompany the shortening days of fall and winter. Many cultures and religions have winter festivals associated with candles or fire. Many of us notice tiredness, a bit of weight gain, difficulty getting out of bed and bouts of "the blues" as fall turns to winter.
However some people experience an exaggerated form of these symptoms. Their depression and lack of energy become debilitating. Work and relationships suffer. This condition, known as Seasonal Affective Disorder (SAD) may affect over 10 million Americans while the milder, "Winter Blues" may affect a larger number of individuals.
The typical symptoms of SAD include depression, lack of energy, increased need for sleep, a craving for sweets and weight gain. Symptoms begin in the fall, peak in the winter and usually resolve in the spring. Some individuals experience great bursts of energy and creativity in the spring or early summer. Susceptible individuals who work in buildings without windows may experience SAD-type symptoms at any time of year. Some people with SAD have mild or occasionally severe periods of mania during the spring or summer. If the symptoms are mild, no treatment may be necessary. If they are problematic, then a mood stabilizer such as Lithium might be considered. There is a smaller group of individuals who suffer from summer depression.
SAD is recognized in the DSM-IV (The American Psychiatric Association's diagnostic manual) as a subtype of major depressive episode. The classic major depression involves decreased appetite, decreased sleep, and often, poor appetite and weight loss. It has long been recognized that some depressed individuals had a "atypical depression" with increased sleep and appetite along with decreased energy. Some, but not all of these atypical individuals also had a seasonal pattern. Some people with winter depression also have mild or occasionally severe manic mood swings in the spring and summer. If these episodes are severe, the individual might be diagnosed with Bipolar Disorder.
What are the patterns of SAD?
Symptoms of winter SAD usually begin in October or November and subside in March or April. Some patients begin to slump as early as August, while others remain well until January. Regardless of the time of onset, most patients don’t feel fully back to normal until early May. Depressions are usually mild to moderate, but they can be severe. Very few patients with SAD have required hospitalization, and even fewer have been treated with electroconvulsive therapy.
The usual characteristics of recurrent winter depression include oversleeping, daytime fatigue, carbohydrate craving and weight gain, although a patient does not necessarily show these symptoms. Additionally, there are the usual features of depression, especially decreased sexual interest, lethargy, hopelessness, suicidal thoughts, lack of interest in normal activities, and social withdrawal.
Light therapy, described below, is now considered the first-line treatment intervention, and if properly dosed can produce relief within days. Antidepressants may also help, and if necessary can be used in conjunction with light.
In about 1/10th of cases, annual relapse occurs in the summer rather than winter, possibly in response to high heat and humidity. During that period, the depression is more likely to be characterized by insomnia, decreased appetite, weight loss, and agitation or anxiety. Patients with such "reverse SAD" often find relief with summer trips to cooler climates in the north. Generally, normal air conditioning is not sufficient to relieve this depression, and an antidepressant may be needed.
In still fewer cases, a patient may experience both winter and summer depressions, while feeling fine each fall and spring, around the equinoxes.
The most common characteristic of people with winter SAD is their reaction to changes in environmental light. Patients living at different latitudes note that their winter depressions are longer and more profound the farther north they live. Patients with SAD also report that their depression worsens or reappears whenever the weather is overcast at any time of the year, or if their indoor lighting is decreased.
SAD is often misdiagnosed as hypothyroidism, hypoglycemia, infectious mononucleosis, and other viral infections.
Epidemiology of SAD
Surveys estimate that 4 to 6 percent of the general population experience winter depression, and another 10 to 20 percent have subsyndromal features. Women with SAD outnumber men four to one. The average age of onset is approximately 23 years of age. The risk of SAD appears to decrease with age. Pilot studies of childhood cases of SAD suggest a prevalence rate between 1.7 and 5.5 percent in children between the ages of nine and 19 years.
For every individual with full blown SAD, there are many more with milder "Winter Blues." The incidence of SAD increases with increasing latitude up to a point, but does not continue increasing all the way to the poles. There seems to be interplay between an individual's innate vulnerability and her degree of light exposure. For instance, one person might feel fine all year in Maryland but develop SAD when she moves to Toronto. Another individual may be symptomatic in Baltimore, but have few symptoms in Miami. Some individuals who work long hours inside office buildings with few windows may experience symptoms all year round. Some very sensitive individuals may note changes in mood during long stretches of cloudy weather.
How is SAD diagnosed?
It can sometimes be hard to tell the difference between non-seasonal depression and SAD, because many of the symptoms are the same. To diagnose SAD, your doctor will want to know if:
- You have been depressed during the same season and have gotten better when the seasons changed for at least 2 years in a row.
- You have symptoms that often occur with SAD, such as being very hungry (especially craving carbohydrates), gaining weight, and sleeping more than usual.
- A close relative-a parent, brother, or sister-has had SAD.
How SAD it treated?
Doctors often prescribe light therapy to treat SAD. There are two types of light therapy:
- Bright light treatment. For this treatment, you sit in front of a "light box" for half an hour or longer, usually in the morning.
- Dawn simulation. For this treatment, a dim light goes on in the morning while you sleep, and it gets brighter over time, like a sunrise.
Light therapy works well for most people with SAD, and it is easy to use. You may start to feel better within a week or so after you start light therapy. But you need to stick with it and use it every day until the season changes. If you don't, your depression could come back.
Other treatments that may help include:
- Antidepressants. These medicines can improve the balance of brain chemicals that affect mood.
- Counseling. Some types of counseling, such as cognitive-behavioral therapy, can help you learn more about SAD and how to manage your symptoms.
If your doctor prescribes antidepressants, be sure you take them the way you are told to. Do not stop taking them just because you feel better. This could cause side effects or make your depression worse. When you are ready to stop, your doctor can help you slowly reduce the dose to prevent problems.
You may feel better if you get regular exercise. Being active during the daytime, especially first thing in the morning, may help you have more energy and feel less depressed. Moderate exercise such as walking, riding a stationary bike, or swimming is a good way to get started.
Theories about how light affect mood and sleep
In 1984, a psychiatrist at NIMH, Norman Rosenthal, published a paper on the use of bright light therapy in patients with this disorder. Since then, a large number of well-designed studies have confirmed and refined these findings. Researchers are still investigating mode by which bright light can lift depression or reset a sleep cycle. One theory is that an area of the brain, near the visual pathway, the suprachiasmatic nucleus responds to light by sending out a signal to suppress the secretion of a hormone called melatonin. Brain studies suggest that there is impairment serotonin function in neurons leading to the suprachiasmatic nucleus.
Initial theories suggested a pathway from the retina to the suprachiasmatic nucleus. However some recent research indicated that bright light applied to the back of an individual's knee could shift human circadian rhythms. (Daily sleep-wake cycle) This suggests that the bloodstream, not just the neurons of the visual pathways, might mediate the biological clock.
How the Light Box is used
Before embarking on a course of light treatment, it is best to have a complete psychiatric evaluation. Sometimes a medical illness or another psychiatric condition can masquerade as depression. Discuss various treatment alternatives with your doctor. Light therapy does take time, and regular use. Like exercise, not everyone who would benefit from it will actually do it on a regular basis. Your doctor will discuss the various types of light boxes or visors available. The time spent in front of the light is related to the intensity of the light source and the distance one sits from the light. The light devices cost about $250 to $500 and often are not covered by insurance. I will often lend out a box for a month so that the individual can see whether it helps before purchasing a box.
Some individuals who use a 10,000-lux box may only need 30 minutes of daily light treatment. However, the amount of light needed varies widely from individual to individual. The light treatment is most often done in the morning, but studies have suggested that either morning or evening light can help SAD. Some people may get insomnia when they use the light in the evening. Initially, researchers felt that one needed full spectrum light. Now, studies suggest that regular fluorescent lights will work as well. UV (ultraviolet) light can damage eyes and skin, so it must be filtered out. It is best to buy a commercially built light box to be sure of the exact amount of light and to be sure that there are no isolated "hot spots" which could damage eyes. Many people still prefer full spectrum (minus UV) light because it is closest to natural lighting.
The individual measures the distance from her face to the light source. This measurement is important, and should be repeated daily for several days and occasionally after that. The light needs to strike one's eyes, but one does not need to look directly into the light source. It is fine to occasionally glance directly into the light. Many people read a book or eat breakfast while using the lights. Sitting still for 30 minutes to several hours is not an option for some people. For these people, the light visor is an option. Others are able to take one of the compact light boxes to work and use it for several hours. It is best to use the light source in an uninterrupted time block, but it can be helpful even with some interruptions.
Long term treatment compliance is often more difficult than one might initially anticipate. This is an important reason to have a professional monitoring. Having to account for your regular use (or the lack thereof) is a powerful motivator. It is also helpful to have an outside objective individual to help monitor your response to the treatment.
Since one of the symptoms of SAD can be difficulty awakening in the morning, some find it helpful to have the light turn on just before they are supposed to wake up. Some individuals like to use a Dawn Simulator. This is a bright light that is programmed to gradually increase its intensity such that it reaches its full intensity a set period before the individual is scheduled to awaken. Although it is less gentle, some people will put their light box beside their bed and hook it up to a timer set to turn on shortly before awakening.
Some people like to use full spectrum light bulbs for everyday household use. There is no evidence that these low intensity bulbs affect mood or sleep phase. Your plant light will not cure your SAD. Your 10,000-lux light however, may be nice for some of your plants.
Side Effects of Light therapy
Potential side effects of light therapy are rare and most often include jitteriness, a feeling of eyestrain and headache. Light therapy, like antidepressant medications, occasionally will cause someone to switch into a manic state. There has been debate on whether there might be long term retinal effects, but none have been documented when lights with proper screening of UV wavelengths are used. Individuals taking certain medications such as Lithium, tricyclic antidepressants, and neuroleptics and individuals with conditions such as diabetes or retinal degeneration should be monitored by an ophthalmologist. Because this form of treatment is fairly new, many doctors recommend a baseline eye exam and annual monitoring.
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