Seasonal affective disorder doesn’t only happen in the winter

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Many Seattleites are well acquainted with the idea of seasonal affective disorder: Shorter days and less daylight in the winter can lead to significant mood changes and fatigue.

Millions of Americans experience seasonal affective disorder in the winter, and it’s much more common in women than men, according to the National Institute of Mental Health. Some experience a milder version of the “winter blues,” and for others, symptoms are more serious.

But the Pacific Northwest’s short, gray days this time of year can be a relief for people who experience the opposite: seasonal depression in the summer. Summer seasonal depression is much less common, but can lead to insomnia, poor appetite, agitation and anxiety.

Kelly Rohan, a professor of psychology at the University of Vermont, has researched seasonal affective disorder for years. She explained how seasonal changes can affect our mental health and well-being throughout the year, and what we can do to cope.

This interview has been lightly edited for length and clarity.

What misconceptions do you often hear about seasonal depression?

That it only affects a minority of people and that it’s less severe than depression overall. Yes, it’s going to be less prevalent than depression, because it’s a subsample of people with depression who have a recurrent pattern that happens to follow a seasonal course. 

However, it strikes annually, and the average length of a winter depressive episode is five months. So, you know, rinse, repeat, do it all over again every year. These people are going to spend a substantial proportion of the year struggling with significant depression symptoms that interfere with quality of life, ability to function, ability to pursue important goals that they want to pursue. I think it’s a really important public health challenge.

What distinguishes true seasonal depression from the feeling that a lot of people might have of being ready to slow down in the winter or sleep a little more? What signs should people know about that might make them want to seek help from a professional?

I guess that’s another misconception, that everybody has seasonal affective disorder, especially in the high latitudes like yours or mine. Seasonality is a broader construct, referring to the degree to which your mood and behavior changes. 

Picture a bell-shaped curve. People with seasonal affective disorder, meaning clinical depression that recurs annually and follows a seasonal pattern, are the extreme tail, and then there’s the rest of us at a high latitude that are going to experience some symptoms. It’s really a minority of people that have the clinical depression that would probably warrant a conversation with at least a primary care provider, if not a mental health practitioner, to try to identify a helpful treatment.

The symptoms are things like feeling persistently down or sad, losing interest in things you usually like to do. Fatigue is probably the universal symptom. Also trouble concentrating, changes in sleep — which could go in either direction from insomnia, difficulty sleeping, to hypersomnia, sleeping too much.

Craving and eating more carbohydrate-rich foods, starches, sugars or both, and often packing on significant weight gain. Really low self-esteem to the point of feeling worthless or having a lot of guilty thoughts from one’s past. In really serious cases, of course, thoughts of death or suicide.

I think summer depression isn’t something people are generally as aware of. How does the disorder present in summer compared to winter?

It’s a minority of folks who identify with a summer pattern of their depression, and therefore it’s much less researched. In winter, SAD people overwhelmingly report that pattern of eating more, gaining weight, sleeping more, people with summer SAD were reporting the opposite. They were reporting a pattern of insomnia, loss of appetite, loss of weight. 

There was a study with one patient who did a five-day experimental treatment where they were confined to air conditioning in the house and agreed to take cold 15-minute showers several times a day. This greatly improved her mood to the nondepressed range, and she then relapsed nine days after stopping those treatments.

What seemed to trigger their depression was sensitivity to heat and humidity, as opposed to, say, too much light. People with winter SAD identify the trigger as the short days, so the trigger seems to be different.

Are there any other differences between summer and winter SAD that we should be aware of? 

(The National Institute of Mental Health) did a study and looked at people in different latitudes: Nashua, N.H.; New York City; Bethesda, Md.; and Sarasota, Fla.

It was suspected that maybe in summer, you’d see the opposite of what we see in winter SAD, which has an increase in prevalence the farther away from the equator you are. The summer pattern was quite rare and didn’t show any kind of relationship with latitude, at least then. I suspect that summer seasonal affective disorder is becoming more prevalent, because the trigger is getting worse. The heat and humidity is getting worse over time.

What interventions can be helpful in managing seasonal affective disorder at different times of the year?

With winter, there are three what I would deem to be evidence-based treatments. Prescription drugs like ones that are used to treat depressions — the SSRIs, selective serotonergic reuptake inhibitors — there’s enough double-blind, randomized, controlled trials to support the efficacy of those drugs.

The other two treatments are bright light therapy, which has a large research base from trials around the world to support the efficacy of daily timed exposure to bright artificial light upon waking. There is no one-size-fits-all prescription, because you could walk into Costco and walk out with a happy light. I think of these as medical devices, and I don’t know why they’re not FDA regulated.

Side effects (of light therapy) can be headaches, eye strain, feeling wired; rare but serious side effects include the possibility of mania or hypomania, elevated mood. It’s quite rare, but I recommend doing light therapy under the supervision of somebody who knows about light therapy, to make sure you’re buying the right thing and using it appropriately. 

The third treatment is cognitive behavioral talk therapy. 

So those are the three for winter, and it sounds like treatment in summer has not been researched as much.

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It has not. We don’t have any randomized clinical trial that has tested the air conditioning plus cold showers intervention, from a single case report by Norman Rosenthal. I do know that practitioners that specialize in SAD do frequently use something like that, like a thermo regulatory intervention, to augment one of the evidence-based treatments for depression like an antidepressant medication or an evidence-based talk therapy.

You’ve been working on a pretty extensive clinical trial focused on treatments for SAD, right? Tell me more about that.

We’re trying to understand how cognitive behavioral therapy and light therapy work at the level of biomarkers, what’s changing in the body as depression improves seasonal affective disorder. Is there a certain biological profile of a patient who might be a better candidate for one treatment over the other? Those are the kinds of questions the study is designed to answer.