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The days are short, the rain is plentiful and light is scarce. Ladies and gentlemen, welcome to Northwest winters.

While many of us just feel nostalgic for those long summer days and hot August sun, there are others who suffer the distress of the darkness more.

If you feel a recurrent depression that coincides with the fall and winter months, it might be time to talk with your doctor about seasonal affective disorder or, as it s also known, SAD

SAD is a variation of mild depression. One of the hallmarks of the disorder is its onset during October and November when the days get short, and then its departure when the spring arrives. Sufferers will notice symptoms like feeling sluggish and sad, an increased appetite and weight gain, decreased self-esteem and poor concentration.

The cause of SAD is more clinical than simply feeling the winter blues because of a few cloudy days. One contributor is the lack of morning light. Morning light tells our bodies to wake up and it sets our body clocks, also known as our circadian rhythms. Since the fall months have limited morning light, our circadian rhythms can become disturbed and our sleep-wake cycles can shift. This shift can affect the quality of our sleep, which in turn can lead to mood disorders, lack of energy and feeling depressed.

One of the ways to regulate our circadian rhythms and treat SAD is with Bright Light Therapy. Bright Light Therapy includes sitting in front of a special light frequency for about 30 minutes at the beginning of each day, and the idea is that this process mimics morning light.

To learn more about SAD, how our circadian rhythms factor into the disorder, and how bright light therapy is used to treat SAD, Dr. David Avery, Professor Emeritus in the Department of Psychiatry at the University of Washington School Of Medicine answered a few frequently asked questions below.

Dr. Avery studied SAD specifically for 15 years from 1985-2000, and is also renowned around the world for his clinical expertise in the treatment of mood disorders. Dr. Avery s other research includes circadian rhythms and temperature regulation in depression and light therapies of seasonal affective disorder (SAD).

Frequently Asked Questions

What is SAD, and what are the symptoms?

Winter depression (Seasonal Affective Disorder, SAD) is characterized by hypersomnia (excessive tiredness), low energy, increased appetite, weight gain, and depression. Typically, patients with winter depression feel fine in the summer; however, in the fall and winter they experience not only decreased mood, but also changes in sleep, energy, and appetite.

How and why does SAD occur?

Winter depressives show an abnormal relationship between their 24-hour circadian rhythms (body clocks) and sleep. Bright light, the best-documented synchronizer of circadian rhythms, acts by shifting the circadian rhythms to a more normal time. In winter depressives, the timing of circadian rhythms, such as melatonin or core body temperature, occurs much later compared with non-depressed controls who are on a similar sleep-wake schedule.

What happens to your body when your circadian rhythm is abnormal?

When the timing of the circadian clock relative to sleep is much later than normal, the clock is said to be phase-delayed , and the patients experience hypersomnia.

For the phase-delayed individual, the temperature minimum (which normally occurs in the middle of sleep) is occurring at about the time the person is scheduled to wake up. One of the most disturbing symptoms for SAD patients is the difficulty awakening in the morning. The patient may feel as though it is the middle of the night when his alarm clock rings; the data suggest that physiologically it may be the middle of night. This situation may be analogous to the jet lag one might experience on a flight from the West Coast to the East Coast. Under those circumstances, it might be 7 a.m. Eastern Time, but the body clock is still on Pacific Time, 4 a.m. Unlike the person who experiences jet lag, the winter depressive lacks the synchronizing effects of bright light to readjust the body clock, and remains in this state until spring arrives, and the morning sun is able to shift his circadian clock.

Why is it important to have a regular sleep-wake cycle? How does sleeping in on the weekend relate to SAD?

Having an irregular sleep-wake cycle (and light-dark cycle) may be analogous to a self-imposed jet lag.

A common sleep pattern in our society is staying up late on Friday and Saturday night and sleeping late on Saturday and Sunday mornings. Sleeping until 10 a.m. (usually in the darkness of the bedroom) may allow us to catch up on sleep but also allows the body clock to drift clockwise (phase delay). Furthermore, staying up late usually means light exposure in the late evening and sleeping late usually means less morning light. Both late evening light and morning darkness favor a further delay of circadian rhythms.

Our patients with SAD, in the summer when they are euthymic, wake up only a half-hour later on weekends compared with weekdays. However, in the winter when depressed, these same SAD patients sleep in on average about 2 hours later on weekends compared to weekdays. In effect, this is analogous to a person on the West Coast flying to Hawaii on Friday night and then flying back on Sunday night.

Can taking supplements like Vitamin D or melatonin stave off SAD?

The data on Vitamin D is not strong.

Is SAD more prevalent is Western Washington?


We only have data indicating the SAD is worse with increased cloud cover and anecdotal information.

As might be expected from a disorder related to a decrease in ambient light, the incidence increases with latitude, with about 10 percent of the population at the latitude of New Hampshire experiencing a major depression each winter. Only one percent of the population does in Florida.

What is Bright Light Therapy and how does it treat SAD?

For the typical winter depressive who has excessive sleep and has difficulty waking up in the morning, bright light soon after awakening is indicated. The bright light therapies range from 2,500 lux (about 300-footcandles) for two hours to 10,000 lux for a half-hour. These light intensities are similar to that of a cloudy day and about five to 20 times greater than the brightness of a bright, well-lit office. A dose of 10,000-lux luminance for 30 minutes gives a therapeutic response similar to 2 hours of the 2,500-lux light.

How soon after using Bright Light Therapy will you notice a difference? Do you have to continue using it?


Usually it takes three or four days for a patient to notice a significant response. The response is usually substantial within one to two weeks. The maximal response from a given dose of light may not be optimal for four weeks.

When the light treatment is stopped, relapse may begin within three to four days. After patients have responded to the bright light, some are able to maintain a therapeutic effect with a shorter duration of bright light exposure. If there is no response after the first two weeks, then the duration, intensity or timing of the lights could be altered.

Are there any dangers associated with Bright Light Therapy?

Occasional patients experience headache, insomnia, or eyestrain. There have been several instances of hypomania or mania associated with bright-light treatment. However, these instances have been resolved with the discontinuance of the bright lights. Appropriate precautions should be taken to avoid any possibility of eye discomfort or injury. Persons with diseases of the eyes or those taking photo-sensitizing medications should check with their physician before using bright light.

What is Dawn Simulation?


A newer treatment of SAD is dawn simulation, a lower level of light that gradually increases to room light level in the early morning before awakening. Although the eyes are critical for the therapeutic response, the eyelids are translucent to light. In addition, the retinas are especially sensitive in the early morning hours and even this low intensity of light may shift the body clock. Although the database is smaller, dawn simulation appears effective and is as effective as bright light therapy. Some patients find bright light therapy inconvenient and may prefer dawn simulation. Dawn simulation and bright light therapy are not mutually exclusive; together they provide a light environment that more closely resembles a summer morning.

What can we do other than Bright Light Therapy?

Increase daytime light exposure. Get outside. Outdoor light (even on a cloudy day) is much brighter than indoor light. For most people, outdoor light soon after awakening is especially helpful. You may also put your bedside lamp on a timer so that the light comes on 15 minutes before your desired time of awakening.

Decrease nighttime light exposure: Dark therapy. Decrease evening light exposure 2-3 hours before desired time of going to sleep especially if you have difficulty getting to sleep. If you do wake up in the middle of the night, do not turn on lights unless it is necessary for safety.

Keep in mind that many of us when we were younger did not have to follow these guidelines and seemed to sleep just fine. This fact does not disprove the principles noted above. As we age, the body clock is more difficult to synchronize, and sleep often becomes more difficult. We may have to change some habits in order to improve our sleep!

If you would like a therapy light for home use check out the Phillips goBlue light or the SunTouch Plus light.

One of the big takeaways from Dr. Avery s advice is to aim to make your sleeping schedule as regular as possible in order to regulate your circadian rhythm and alleviate SAD. The Northwest lacks significant morning light in the fall and winter months, and since morning light is essential for a normal circadian rhythm, Bright Light Therapy is an options that can mimic the benefits of morning light.

It s also important to note that SAD is a type of depression and there are different scales of the severity SAD. Dr. Avery recommends speaking with your doctor if you feel you might be suffering from SAD.

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