GW MFA Psychiatrist Daniel Lieberman, MD, Discusses Seasonal Affective Disorder

December 20, 2021
Daniel Z. Lieberman, MD

Seasonal affective disorder, or S.A.D., can be a formidable consequence of shorter days, colder weather, and weaker sunlight. However, it’s highly treatable, thanks to treatments such as light therapy. Even walks outside can help boost your mood, says Daniel Z. Lieberman, MD, professor of psychiatry and behavioral sciences and vice chair for clinical affairs at the George Washington University (GW) Medical Faculty Associates (MFA). Here, he explores the cyclical nature of both human biology and Mother Nature, how our mental health can be affected, and how to effectively use light therapy.

What is seasonal affective disorder?

Lieberman: Seasonal affective disorder is a kind of medical mood disorder that’s brought on by the change of seasons. The symptoms are very, very similar to major depressive disorder, which is sometimes called clinical depression. They can be quite serious, and they can cause a great deal of subjective distress, personal distress, and also impairment. People have a lot of difficulty interacting with others, getting work done, and just taking care of household chores.

Why does S.A.D. happen?

Lieberman: It seems more to do with the way almost all organisms on Earth evolved: [synchronizing] themselves with the circadian rhythm of light and dark as the sun rises and sets. So many organisms have timekeepers, and in the human body, every single cell has its own timekeeper. Light is the primary way that these timekeepers are affected, but other things matter as well, such as what time you eat, how you socialize, and when you exercise.

Light and dark are incredibly important to human beings, and when the days get short, it seems to be a genetic effect that changes the balance of chemicals in the brain and leads to symptoms such as sadness, tearfulness, low energy, and cravings for sugar and comfort foods. In a worst-case scenario, it can even lead to suicidal thoughts.

How common is S.A.D.? Would most people experience this at some point in their life?

Lieberman: I think that most people who hear about it sort of nod their head and say, “Yeah, I think I know what you’re talking about.” For most people, that would be called “winter blues,” where their mood goes down, they have less energy, they tend to be kind of sluggish. Maybe they crave comfort foods, but it’s not really causing what we would call suffering, and it’s certainly not preventing them from functioning the way they usually do. Seasonal affective disorder is much more serious and much less common. Different studies have found different numbers, but maybe 5% [of people] is a good estimate; 1 in 20 people experience it to the degree of severity that it is really diagnosed as a medical illness.

Are there any risk factors for those who are diagnosed with S.A.D.?

Lieberman: The biggest risk factor is having another kind of a mood disorder. If somebody has experienced a non-seasonal clinical depression, they’re going to be at very high risk for worsening during the wintertime. People with bipolar disorder, which is a cyclical mood disorder, are also at very high risk because the seasons seem to really feed into that cyclic pattern. So, a preexisting mood disorder is an important risk factor.

Another factor is that some people are just simply more sensitive to changes in circadian rhythms. If you’ve ever traveled overseas, some people have an easier time adjusting to a new time zone. Some people have a much harder time. It’s the latter who are going to be more vulnerable to the possibility of a seasonal depression. There also seems to be a genetic component. If family members experienced seasonal depression, then you're going to be at higher risk as well.

How effective is light therapy as a treatment for S.A.D.?

Leiberman: Light therapy is a wonderful treatment for seasonal affective disorder. It’s very effective. Most people who use it experience substantial relief. The most wonderful thing about it is how quickly it works. Psychiatrists are used to prescribing medications that take weeks to work, and it’s so hard watching patients suffer through that waiting period. Bright light, by contrast, works right away. Most people who use it feel better the same day they start using it.

Another great thing about light therapy is that it is very, very limited in terms of side effects. Some people get a little bit of eyestrain, but it’s uncommon. Some will get headaches, that’s uncommon too. Some people feel a little bit over-wired, a little agitated, and they just need to reduce the amount of time they use it. The vast majority of people have no side effects at all.

You can purchase these lights on Amazon, but there are two important criteria for them. The first one is brightness. They’ve got to put out 10,000 lux. Most people are surprised the first time they turn these on and see how bright they are. The second criterion is that they must not emit ultraviolet radiation. At that level of brightness, ultraviolet radiation can damage the eyes.

The very best time to use light therapy is first thing in the morning for maybe 20 to 30 minutes. If that’s not possible, using it at lunchtime for 60 minutes is almost as good. They should not be used in the afternoon because that will cause insomnia.

One more thing: The intensity of light decreases by the square of the distance from the light. In simple terms, that means how close the lamp is to your face matters a great deal. Ideally, it should be 12 to 24 inches away and shining right at your face, but you don’t need to stare at it. You can work on a computer or read a book while you’re doing your light therapy.

The big disadvantage is that it is inconvenient having to put in that time, 20-30 minutes every single day. People who do it, however, often come to look forward to their sessions because it makes them feel so good.

It sounds relaxing.

Lieberman: It can be relaxing. It can also be a little energizing though. It’s more likely to almost feel like a cup of coffee in the morning.

What else can people do to feel better?

Lieberman: Another approach is to try to increase your exposure in natural light, and the earlier in the day it is, the better. A lot of people are spending more time working from home, and that means that they don’t have a morning commute, which is wonderful. But the downside is that they’re not leaving their homes and getting outside on a regular basis, so they may not get as much sunlight as they’re used to. What I’ve recommended to a lot of my patients is to create a new commute. Wake up in the morning and take a walk around the block for 15 or 20 minutes to get a little exercise, get exposure to sunlight. That will be terrific for one’s health.

When should patients consider seeing a psychiatrist for this kind of depression?

Lieberman: If they’re having thoughts about suicide or about their death, that’s a clear indication that they’re dealing with a medical illness that’s really going to benefit from consultation with a specialist. Short of that though, I would say to see a specialist if: it’s affecting functioning; if people feel like they’re just not performing as well at work; if they’re kind of irritable and snappish with their loved ones; if they don’t want to interact at all, and they just want to sort of curl up in a corner and be invisible; or if they’re just not enjoying their life anymore, and the things that usually give them pleasure just seem flat and dull. These are all indications that a medical illness is present and would really benefit from some medical treatments.


To make an appointment with a psychiatrist, visit the GW MFA Department of Psychiatry and Behavioral Sciences or call 202-741-2888.

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