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NIMH Livestream Event on Seasonal Affective Disorder

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MATT RUDORFER: Hello, and welcome to the National Institute of Mental Health Facebook Live and Twitter presentation on seasonal affective disorder. I'm Dr. Matt Rudorfer, a psychiatrist and chief of the Adult Somatic Psychopharmacology and Integrated Treatment Research Program in the NIMH Division of Services and Intervention Research, and I am pleased and honored to be able to speak with you today. On the wall behind me to my left, you can see part of my framed Hippocratic Oath. And in fact, I'd like to begin with words that Hippocrates spoke over 2,000 years ago when he said, quote, "It is chiefly the changes of the seasons which produces diseases," unquote. While most of the time, this observation can be easily dismissed as overstatement, we meet today because, in terms of mood disorders and the coming of the cold weather months, Hippocrates probably had a point. Picture this. It's the middle of a long winter, the latest in the seemingly never-ended string of cold, gloomy days. You look out of your window at your dismay to realize that, even though it's not even 5 o'clock in the afternoon, it's already dark as night outside. So here is the key question. If, at that moment, by some miracle, you could become a bear and hibernate until springtime, would you? You can keep your answer to yourself, though I have my suspicions.

For me, the story of the mood disturbance associated with late fall and beyond, what came to be known as seasonal affective disorder, S-A-D, or SAD, a classic acronym, began way back in the early 1980s as I was starting my fellowship in the clinical psychobiology branch in the NIMH intraneural research program in Bethesda, Maryland. One day, the laboratory chief, Dr. Fred Goodwin, who would later become director of NIMH, summoned us to a lab meeting that was to feature our colleague, Dr. Norm Rosenthal, working with branch chief Tom Ware, presenting his new protocol to study what was described as light treatment of winter depression. Suffice it to say that, at that time, that sounded, to me at least, like an unusual approach to a mysterious condition. Today, most of the mystery is gone, but the challenge of dealing with a potentially serious mood disorder that can reappear like clockwork every year and dominate one's life for several months at a stretch remains very real. In our time together today, I'd like to describe the current view of what is meant by seasonal affective disorder, how our understanding of the factors that cause and contribute to SAD informs the range of available treatment and preventive interventions, and the outlook for the future. If, at any point, you have questions for me related to SAD, please comment on the stream feed, on NIMH's Facebook, or tweet your questions to NIMH's Twitter page, and I will do my best to answer toward the end of my discussion today or after the program, if we run out of time.

It's important to note that I cannot provide specific medical advice or referrals. Please consult with a qualified healthcare provider for diagnosis, treatment, and answers to your personal questions, and to be sure that any underlying medical problem that could be causing or aggravating a mental health condition is identified and addressed. If you need help finding a provider, please visit If you or someone you know is in crisis, please call the National Suicide Prevention Lifeline at 1-800-273-TALK - that's 273-8255 - or visit You can also ask for help in the comments section of this feed and someone from NIMH will assist. All of the websites and phone numbers I just mentioned will also be posted in the comments section of this feed so you can easily access them. Although, at one time, it was believed that seasonal affective disorder was so unique and different from more typical mood syndromes that it was a separate and distinct illness, it is now appreciated that, in fact, the basic issue is not the actual depressive episode, which in many respects is like any period of sub-chronic depression that lasts for months, but rather, it is the timing, the repetitive onset and clearing of the depression keyed to the same changing seasons year in and year out that defines this disorder. The formal DSM-5 diagnostic classification of what we recognize as SAD is termed recurrent major depressive disorder, quote, "with seasonal pattern," unquote.

While the depressive episodes of winter SAD meet the usual diagnostic criteria for major depression, going beyond low mood, to include loss of interest in usual activities, sleep and appetite disturbances, poor concentration, and thoughts of death or suicide, with an impairment in day-to-day functioning, they tend to have much in common with those depressions most associated with bipolar disorder or with hibernating bears in terms of oversleeping, overeating with carbohydrate craving and unwanted weight gain, and the general sluggishness and social withdrawal. In order to establish the distinctive pattern of onset and remission of SAD episodes, the DSM-5 specifies that this sequence must have occurred during at least a two-year period without any non-seasonal episodes occurring during that time. In addition, the seasonal depressive episodes must substantially outnumber any non-seasonal depressions over a person's lifetime. In other words, a single episode of depression, whenever it occurs, is not sufficient to establish the presence of SAD. A diagnostic tool no more powerful than a timeline showing discrete winter depressive episodes over two or more years is often sufficient to confirm a pattern of seasonal depression.

A very important qualifying point is that the diagnosis of SAD does not apply to what the DSM calls those situations in which the pattern is better explained by seasonally linked psychosocial stressors, such as seasonal unemployment or school schedules. So while the term winter blues is commonly used for the mildest, often subsyndromal cases, SAD is not the same as holiday blues or being stressed out by the demands of winter celebrations, or visiting in-laws, the sadness of missing loved ones at this meaningful time of year, or just not liking winter. Although recurrent, summer depressive episodes are known to occur. These are much less common than the pattern of winter depressions we're discussing today. Relief of winter depression in the spring is sometimes dramatic and even hypomanic, leading to a formal diagnosis of bipolar type-two disorder. In terms of demographics, SAD sufferers identify as female rather than male by a very large four-to-one ratio. In most cases, SAD begins in young adulthood and may be accompanied by another mental disorder, such as an attention deficit, anxiety, or eating disorder. Given that SAD is typically linked so close to wintertime, it is not surprising that it occurs most commonly in northern latitudes where the seasonal change is most pronounced. In the US, for example, winter depression is relatively rare in Florida but affects nearly 1 in 10 people in New England.

Scientists do not fully understand what causes SAD. Theories relating decreased sunlight with impaired regulation of neural circuits controlled by the neurotransmitter serotonin, implicated in controlling mood, a deficit perhaps aggravated by low wintertime vitamin D levels, are intriguing but difficult to prove. A growing body of evidence supports the role of chronobiological disturbances related to shortened winter days with important implications for treatment. In particular, light therapy, typically provided by way of daily morning exposure to bright light delivered by a freestanding lightbox, has become the gold standard treatment of SAD. Perhaps the most obvious theory is that SAD represents a deficit in the number of daylight hours or photoperiod in wintertime. For some individuals, the reduced light exposure seems associated with a longer duration of nighttime secretion of melatonin, the body's natural sleep hormone in winter compared to summer. Melatonin produced by the pineal gland overnight in healthy individuals is suppressed by morning light, and perhaps this hypothesized excess melatonin in those with SAD is not turned off by weak wintertime natural light and requires bright light therapy to stop the production of this nighttime hormone and enable the individual to start her day awake and alert.

A related and widely accepted theory of winter depression, generally credited to former NIMH investigator Al Louis, now professor emeritus in the frequently overcast and cloudy state of Oregon, is the phase shift hypothesis of SAD, according to which seasonal depression occurs when the body's natural circadian rhythms, such as those of melatonin and body temperature, which have predictable peaks and valleys over the course of a day and night, are phase-delayed relative to clock time, in much the same way that teenagers tend to have a later natural bedtime and wake-up time than adults. According to this model, light therapy should exert its therapeutic effect by advancing and thereby correcting these phase delays. As with most treatments, the timing, dose, and duration of light therapy are important factors in its success. It is now well-established that light therapy works best in the morning and that light must be absorbed by photoreceptors in the eyes, not the skin. While small lightboxes, such as this one here, are convenient for travel, ideally, the device should be a larger rectangle - at least one foot by one and a half feet - and deliver full-spectrum white light, filtering out potentially harmful ultraviolet rays at an intensity of 10,000 lux, which is about 20 times brighter than ordinary indoor lighting. Most individuals do best by sitting close to the box for 30 to 60 minutes daily early in the morning, during which one can read, work on a computer, eat breakfast, or just relax. In most studies, the majority of SAD patients noticed an improvement in symptoms within two weeks, with daily treatments then continuing throughout the winter.

Other than those with certain retinal conditions, light therapy is very safe for most people. Occasional eye strain or headache usually clears on its own or may require shortening of treatment sessions. However, light therapy is best initiated under professional supervision. It is, in fact, a powerful intervention, and changing sleep patterns in a therapeutic fashion without causing insomnia or unstable mood can be challenging. Caution is required by individuals who are especially sensitive to light, including those with particular health conditions such as lupus or those taking some medications, especially certain antibiotics. From a psychiatric perspective, as is true for any antidepressant treatment, patients with an underlying bipolar disorder are at risk for a switch into hypomania or mania during light treatments and are candidates for concurrent mood stabilizer medication. Follow-up studies have found that the main reason for inconsistent use or premature discontinuation of light therapy is not adverse effects, as is usually the case in medication trials, but rather the inconvenience and hassle of spending up to an hour every morning in front of the lightbox. Ironically, one of the few silver linings of the COVID pandemic, with the dramatic increase in the number of people working from home, is that use of morning light therapy is much more practical when one is not needing to rush out of the home to commute to work. Still, some people are not comfortable with the requirement of sitting in one place in front of the lightbox and may have realistic concerns about the unknown safety of the bright light to children and pets in the home who might be exposed along with the patient.

For these reasons, efforts have been made over the years to perfect a portable light therapy device, such as a visor with light sources embedded in the underside of the bill. Studies of such products proved unsuccessful, however, probably due to the insufficient delivery of the light stimulus to the eye, given the anatomy of the skull and the eye socket. A new approach that is promising but not yet established for SAD treatment is the use of glasses that deliver blue-green light continuously by means of four light-emitting diodes aimed upward toward the eyes from the lower rims, thereby avoiding the anatomic obstacles that impaired the effectiveness of the earlier generation of light visors. The 500 lux of light delivered close to the eyes is said to be equivalent to the use of a traditional 10,000-lux lightbox. The Australian manufacturer of these particular glasses has reported that exposure of the eyes to light and overall adherence are superior for these portable devices compared to a traditional lightbox. And they are pretty lightweight.

Research in people with sleep disorders supported by the manufacturer has documented the ability of light delivered by these glasses to phase-advanced dim-light melatonin onset, or DLMO, the standard measure in circadian rhythm studies with maximum potency of the shorter wavelengths of light that carry the most energy, including blue and green. Here in the US, NIMH supported ongoing research led by Dr. Leslie Swanson at the University of Michigan in women with depression during and after pregnancy associated with phase-delay in supporting the antidepressant effectiveness and the finding of DLMO advanced with the home use of light therapy glasses. However, assessment of whether any of a growing number of affordable, wearable light therapy devices will prove sufficient to deal with the powerful biologic underpinnings of SAD must await definitive, controlled clinical trials. In fact, given the apparent biologic mediation of it and the striking therapeutic effectiveness of standard light therapy, a potential role for psychosocial interventions was late in coming. Driven in large part by NIMH-supported investigator Dr. Kelly Rohan at the University of Vermont, cognitive behavioral therapy, or CBT, a well-established, evidence-based treatment for depression, has been adapted to the specific challenges of winter SAD.

Behavioral activation with scheduling of pleasant events is used to combat winter anhedonia or loss of the ability to experience pleasure. Cognitive restructuring goes beyond typical depressive thought content, as in traditional CBT, to challenge negative thoughts related to the winter season, such as a focus on darkness or winter weather, striving for early identification of negative anticipatory thoughts about winter, and SAD-related behavior changes as signals to implement CBT skills to prevent recurrence. Given the time-sensitivity of the need for intervention, CBT SAD is delivered on a condensed schedule of two 90-minute group sessions per week over six weeks. In an initial six-week controlled clinical trial by the Rohan group of individuals with SAD currently depressed during the New England winter, patients randomized to light therapy or to CBT SAD showed significant and equivalent acute improvement to both interventions, with remission rates in the 50 to 60 percent range. Follow-up of these subjects the following winter found no difference in rates of depressive recurrence between the two treatment groups. However, at the second winter follow-up, those initially treated with CBT SAD showed fewer recurrences - approximately 28% - compared with 46% for the light therapy cohort. These findings suggest greater durability over time of a treatment effect for CBT SAD over light therapy.

As with all types of major depression, for some individuals, antidepressant medication is an important component of an effective treatment regimen. In general, medication choices would be similar to any type of major depression, often first trying a selective serotonin reuptake inhibitor, or SSRI, such as fluoxetine, sertraline, or escitalopram, especially helpful when anxiety, as well as depression, is part of the picture. Serotonin-norepinephrine reuptake inhibitors, or SNRIs, including venlafaxine and fluoxetine, are often recommended for people who do not respond well to SSRIs. They also have reported benefit when pain is involved. While positive results have been reported in some cases with the use of the complementary intervention St. John's-wort, given the photosensitizing properties of this herb, it is generally considered inadvisable to combine with light therapy. Everybody is different, and it can take some educated trial and error to find an antidepressant that, for each person, provides the best balance of reducing symptoms, which can take two to four weeks, while producing as few side effects as possible. Newer, rapidly acting antidepressants, such as intravenous ketamine and intranasal esketamine, have not yet been studied systematically in SAD.

One specific antidepressant, extended-release bupropion, brand name Wellbutrin XL, an energizing medication, has demonstrated effectiveness in preventing the onset of SAD symptoms when taken early enough in the season. In 2006, it became the first and still the only drug to have an FDA-approved indication for use in SAD on the basis of three controlled trials that compared extended-release bupropion begun during the fall in individuals with a history of SAD with placebo. The medication was continued throughout the winter before being tapered and discontinued in early spring. Greater reduction or avoidance of winter depressive symptoms were seen in the active treatment groups. In the years since, there have been no studies reporting any other antidepressants beyond bupropion XL, now available as a generic, for SAD prevention. There's good agreement, though, that starting treatment with whatever modality before full-blown symptoms emerge is an important goal.

As with all forms of depression, many SAD patients respond best to the use of multiple treatment approaches at the same time: for example, taking medication while also undergoing daily light therapy. Vitamin D supplementation can be a helpful augmentation agent for some but is not regarded as sufficient as a standalone treatment for SAD. Aerobic exercise and spending time outside, especially early in the day, scheduling pleasurable activities, and being around family and friends can enhance any treatment regimen. Most individuals with winter depression can benefit from a personalized approach involving proper identification and diagnosis of the syndrome and treatment with one or more of the growing list of safe and effective interventions to enable good functioning and good cheer, even when it's dark at 4:30 in the afternoon.

To close the formal part of today's presentation, I want to remind everyone that NIMH conducts and supports a broad range of research at the NIH Clinical Center in Bethesda and at universities and clinics around the country, including clinical trials that look at new ways to prevent, detect, or treat a range of mental disorders, including SAD. For more information about clinical research and the potential benefits and drawbacks of participating in the clinical trial, please visit the clinical trials page at, and be sure to talk to your healthcare provider about whether any of the listed trials in your area could be right for you. Now, I believe we have time for a few questions.

Okay, this might be the closest I come to Final Jeopardy, so forgive me if I answer in the form of a question. No, I'm kidding. Question: any data on those who deal with SAD and then move to the South? That's an excellent question. I'm not aware that there's any data, but there is very strong anecdotal evidence of the helpfulness of moving to the South and even a vacation, if possible, in Florida or the Caribbean has been reported - now, extensively - by many people as being beneficial. So as long as travel is safe and that is possible, that certainly is a general recommendation for folks during the winter. We do have a question about SAD in the summertime from somebody who lives in South Texas and deals with SAD in the hot weather, when they need to avoid the sun at all costs. That is certainly a real phenomenon. There is much less research done on that because the incidence seems to be much less. And I'm glad that arose. Some of the symptoms seem similar. That is, depression is depression is depression. But there are other unique factors of, for example, anger attacks have been reported more commonly in summertime depressions. And I think that this is a good place to mention that there certainly are areas in need of further research, and this is one of them, and I hope we will revisit that.

Okay, a question about diet; specifically, adding good fats and less refined carbs. So the short answer is yes, that's a good idea. However, A, most of the research has focused on omega-3 fatty acids, and the literature is quite mixed. In almost any disorder that's studied, there's a couple of positive studies, usually followed by one or two iffy studies. And so I think the jury is still out. The carbohydrate question has really vexed the field for the simple reason that, as I mentioned, carbohydrate craving tends to come with the territory of winter depression, so that can be really hard to enforce. But certainly, attention to at least a balanced diet, if not the most healthful in the world, is a good strategy during the winter. Okay, is it possible to get very tired after light therapy in the morning? Yes, I think that that's a very good question because, when we talk about medications, often, we think, "Well, if you take, say, your antidepressant and it seems to make you tired, well, maybe we need to switch the timing." And often, there are people who take their antidepressants in the morning, and if it seems to reduce their energy, they switch to nighttime. Here, that's a real problem because light therapy you want to use as early in the day as possible, the whole point being to phase-advance the delayed circadian rhythms, and taking it later in the day would have the opposite effect and could make things worse.

So the usual approach would be, if your light therapy is creating problems-- well, certainly, if it's creating any eye problems, you want to check with your eye doctor to be sure it's safe for you. But otherwise, the usual approach would be to reduce the length of the session, for instance, starting with only, say, 10 minutes rather than starting with 30, and try to gradually increase that. And the feeling would be that a shorter session of light therapy in the morning for most people with SAD is better than none at all. Okay, I think we've got time for one more question. How can we explain the presence of SAD in hot countries? So the research on latitude is much more complicated than what we see in the United States, where it's fairly straightforward. And basically, the feeling is that, in many countries, there are genetic influences, one way or another, that might have affected the population, whether to increase or decrease the vulnerability to SAD. So that, for example, in Iceland, I believe the incidence of SAD should be very high but in fact, is very low, and the thinking that there are genetic explanations. But I think it's fair to say that, as with mood disorders across the board, when it comes to cause and effect, there are still many more theories than proven facts, and I don't think we can explain the phenomena of seasonal depression fully as of yet.

And, okay, final-final question: I'm asked to repeat the name of the investigator at University of Vermont, which I am happy to do. That is Dr. Kelly Rohan, R-O-H-A-N. And she actually began her research here in Maryland at what was then the Naval Hospital, now Walter Reed, and moved her operation to Vermont, where the incidence of winter depression is extremely high. And I don't believe she's ever had any recruitment problems at all. But the good news is she's getting a lot of very valuable data, which you will continue to see reported as time goes on. Okay, so I believe that we've now come to the end of our program. Let me just mention that, if I was not able to get to your question, we will do our best to provide an answer offline. So I want to thank you all for joining me today for this important and timely discussion. Please reach out for help if you need it. As a reminder, the contact information for the National Suicide Prevention Lifeline here on your screen is also posted in the comments, their phone number of 1-800-273-TALK. That's 273-8255. And for more information on seasonal depression, please visit

I'd like to offer my special thanks to Setareh Kamali, the digital media lead in the NIMH Office of Science, Policy, Planning, and Communications, who expertly organized all aspects of today's program, and the team of Chris McQuaid and Janice Nierstedt-Keegan, whose outstanding sign language interpretation ensured that today's presentation was welcoming and informative to all. On behalf of NIMH, I wish you all a safe, healthy, and non-hibernating holiday season. Thanks, and bye for now.