Insights into Psychology

What Is… Seasonal Affective Disorder (SAD)

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In this series, I dig a little deeper into the meaning of psychological terms. This week’s term is seasonal affective disorder.

Seasonal affective disorder (SAD) is a subtype of depression with symptoms that occur based on a seasonal pattern. Typically, depressive symptoms occur during the winter, but other patterns are possible. For example, depressive symptoms may appear in the spring, or anxiety symptoms may show up in the summer.


The potential symptoms of SAD are the same set of symptoms that can occur with other types of depression. However, winter depression tends to be more likely to be associated with oversleeping, increased appetite, and weight gain, while in non-seasonal depression, insomnia and decreased appetite are more common.

People with bipolar disorder who have a seasonal element to their illness may be diagnosed as bipolar I or II with seasonal pattern. Seasonal fluctuations are more common with bipolar II than bipolar I. Spring and summer may trigger the onset of mania or hypomania.

Other features

Approximately 6% of Americans experience SAD, while around 14% experience seasonal dips in mood that don’t meet the full diagnostic criteria for a depressive episode. One survey found that 20% or Irish people experience SAD. It’s more common in females than males. In terms of age, risk increases with age up until the mid-50’s, and then drops off after that. There’s some indication that there’s a genetic component to risk for SAD.

The exact cause of SAD isn’t clear. Rates of SAD are elevated at higher latitudes that have less light in the winter, which may effect melatonin production by the pineal gland in the brain. This can affect serotonin production, as melatonin is a precursor to serotonin. Serotonin is thought to be the neurotransmitter that plays the biggest role in SAD.

Some research has shown that almost 1/4 of people with SAD also have a personality disorder. While the disorders and their causes are distinct, it may be that there is a personality component that contributes to risk for SAD.


Getting regular exposure to outdoor light (even on cloudy days) and physical activity may also be helpful. In terms of medication, the SSRI antidepressants and fluoxetine are commonly used.

Light therapy

Light therapy one option that can be effective for treating SAD, although research findings have been mixed. Some studies have shown that it’s approximately equal to SSRIs in effectiveness. There should start to be some positive effect within a few days. If there’s no benefit after two weeks, longer exposure may be needed.

Light boxes emit fluorescent light and come in different intensities, measured in lux. Using a 10,000 lux light box would require half the amount of time as a 5000 lux box to get the same effect. Lights can be cool-white or broad spectrum. Dawn simulators may be helpful for sleep and circadian rhythm, but for SAD, they’re not as effective as a light box.

The typical recommended time for depression is 30 minutes for a 10,000 lux light box. For bipolar, a shorter amount of time may be better. You should sit 30-60 cm (about 1-2 feet) away from the box, at an angle that allows the light to shine in your eyes without staring directly at it. Getting the light in your eyes is more important than getting it on your skin, which is the opposite of how light boosts vitamin D production. Treatments should be done soon after waking up in the morning.

Getting personal

I live on the wet west coast of Canada, just north of the 49th parallel. The biggest issue in the winter here is that it rains a ton, so the sun doesn’t make an appearance very often. While I find cloudy vs sunny days make a transient difference in my mood, winter doesn’t seem to affect my symptom patterns overall. However, since early on in the course of my illness I’ve had a consistent seasonal pattern of a major drop in mood starting in late August and lasting through September.

I have a light box that I sometimes use in the winter, but I don’t notice much of an effect from it. I actually prefer the warm glow of my Himalayan salt lamp; it’s not the right kind of light to have the benefits of a light box, but I find it soothing, which is not the case with my cool-white SAD light.

Do you have a seasonal component to your illness?


You can find the rest of the what is… series in the Psychology Corner.

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Managing the Depression Puzzle takes a holistic look at the different potential pieces that might fit into your unique depression puzzle. The revised and expanded 2nd edition is now available on Amazon.

For other books by Ashley L. Peterson, visit the Mental Health @ Home Books page.

20 thoughts on “What Is… Seasonal Affective Disorder (SAD)”

  1. I always suspected I had, but to my by the last 2 years being more self-aware, I don’t think I do, because last year was more my mental health and this year, I don’t feel like any other year. If I do have it, then it’s a very slight to not affect me bad because it’s not that bad as I thought going on the past years.

      1. It’s more now in the last few years as I learn about how I can be. It’s just being more self-aware than I was years ago and still learning. So yes, it’s been interesting.

  2. I’m taking 60 mg of Prozac preventively right now, and I’m sure the doctor will let me go up to 80 if need be. That reminds me, I need to call and make an appt. I also hung some fluorescent lights in every offshoot of my room (which is shaped like a giant plus sign) so that everything isn’t cast in shadows. It’s not exactly the same as using light-box therapy, but I figured I’d be happier with everything lit up rather than all dark and spooky up here. There used to be awful, nonexistent overhead light up here, and it felt wasteful since I took the time and energy to make the room so colorful and pretty.

    Great article! I didn’t know that stuff about anxiety in summer, although I did know about warm-weather mania. Reading about the geographic causes makes me so glad I live in Louisville and not someplace worse from a winter perspective! Oh, geez.

  3. I think a lot of people will feel the effects of seasonal changes to different degrees, and for those with SAD it can have a marked impact on mood and health and life in general. I struggle with the cold and feel it even in warmer weather, so autumn/winter are harder for me mentally, factor in darker days and Vit D deficiency and things get a little murkier. It’s interesting with the SAD lamp and it not helping you much, it seems like something you have to try for yourself to see whether it does anything or not. I’ve never tried one myself, nor a Himalayan salt lamp which you find better, though I do hear those are supposed to be good throughout the year. xx

      1. Research on Vitamin levels appear consistently low in people who live in the
        northern areas. . .like me in Montana. After educatiing myself, I now take
        20,000 units a day. It’s only been 10 days and I feel like a new person. This
        is a great subject to Google!

  4. This is such a great post; I feel as if hardly anyone really accepts that there is such thing as Seasonal Affective Disorder and they just act as if they have it without understanding. I hope you get better; a few years ago, I thought that I was struggling with this but after a long summer, I was more able to deal with a very cold winter and I just got better from there. Good luck!

  5. I grew up on the far west coast of British Columbia and was/am effected by Seasonal Affected Disorder. Even in the years I struggled the whole year with depression, mental health in general, it would be much more deeper and a lot harder to cope in the winters. As cold as the east coast is, I like the sun. 🙂

  6. I cannot say with certainty if I have SAD but I’ve certainly felt some of its symptoms, mostly a severe dip in my mood and a general depressive lackluster towards everything. It’s gotten better this year because of exercise, and even on cloudy days I bundle up and make myself go outside to do grocery shopping. Getting out helps immensely as does doing physical exercise. Even walking a little bit faster for a few blocks to get my heartrate up feels great. ☺

  7. I suffer from Fall/Winter S.A.D. I wasn’t diagnosed until about two years ago too. I just thought because a lot of bad things have happened to me in the past during that period of time, that I was just extra depressed. My condition has an additional component in that I have rosacea which is exacerbated by exposure to sunlight…so using the light or the box is not a good thing for me. I just keep plenty of anti-anxiety medication on hand, and I take my anti-depressant religiously. It has to do. I also try to avoid situations that trigger emotional responses like more sadness.

  8. I do get more depressed in the winter, especially when there are several cloudy days in a row. I’ve been meaning to ask my therapist about a light box or something, but there hasn’t been a good time… maybe I’ll just get up the courage and go for it the next time we talk. Like many issues in my life, I’ve been aware of it for a few years and suspected SAD, but didn’t think it was “bad enough” to be worth mentioning or getting help for. Looking back, I remember many, many times being SO happy at sunny days. Haha.

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