IRA FLATOW, HOST:
This is SCIENCE FRIDAY. I'm Ira Flatow. Have you noticed how short the days are getting? Is it having an effect on you? Maybe you have a little trouble rolling out of bed each morning or you're feeling a little bit sluggish, a little depressed even.
Well, the good news is it's a normal reaction to less daily sunlight, but why do you get the winter blues? And is there some evolutionary advantage to all of this?
In some people the depression can be more acute: Seasonal Affective Disorder, SAD. What can they do about it? That's what we'll be talking about. Our number is 1-800-989-8255, 1-800-989-TALK. Dr. Richard A. Friedman is a professor of psychiatry at Weill Cornell Medical College here in New York. He is here in our New York studios.
Welcome to SCIENCE FRIDAY, Dr. Friedman.
DR. RICHARD FRIEDMAN: Thank you.
FLATOW: What exactly is going on that causes this seasonal depression?
FRIEDMAN: Well, what we think is going on is that people are essentially beginning to respond to the fact that the days are getting shorter, and so daylight gets shorter during the winter. And there are a group of people that respond by feeling lethargic and tired and sad and they want to sleep more and eat more and have less sex.
FLATOW: How do you know if you're one of the people who has this full-blown Seasonal Affective Disorder?
FRIEDMAN: Well, because you have a repeated pattern of depression the same time every year. That is, when the photoperiod starts to get short and the winter is coming on, and then when the winter lets up and spring comes, you start to feel good again.
FLATOW: Do we actually know what's going on in your brain when this happens?
FRIEDMAN: Well, we know what's going on in other animals who've displayed behavior that's somewhat like humans; that is, a kind of hibernating behavior, so we think it's linked to the hormone melatonin, which basically is the signal that tells your brain that it's nighttime.
FLATOW: So could you just take melatonin pills and solve it that way?
FRIEDMAN: You can manipulate melatonin, but it's not as effective as light, so far.
FLATOW: So you want to get more light, artificially, if you have to, right?
FRIEDMAN: Right. You want to basically fool the brain into thinking winter's not here and that, you know, the days are actually not getting shorter.
FLATOW: And how do you do that?
FRIEDMAN: You administer light in the morning and you essentially tell the brain, hey, it's time to wake up. It's actually daylight.
FRIEDMAN: So, basically, what you want to do is override the signal from the season that is telling you the days are shorter, the photoperiod's getting smaller, and you can override it with light.
FLATOW: Now, do you need to get a prescription for a light box or can you go out and buy one yourself? Or can you self-diagnose this or is it better to - maybe you could try it and see if it works.
FRIEDMAN: Yes. You know, light is highly effective, very safe, very few side effects. Most people who have seasonal depression are aware of the pattern. You don't need a prescription to get a light box and you can buy one yourself on multiple websites.
FLATOW: 1-800-989-8255. Someone is tweeting us, saying what about a tanning bed. People get into tanning beds. Is that the same thing or will that help? But you're going to get brown at the same time.
FRIEDMAN: Well, that's a bit dangerous because the exposure to UV light is carcinogenic and it's harmful. And basically, you want visible light spectrum and you're getting - you don't want to be exposed to UV light.
FLATOW: And for how many hours a day?
FRIEDMAN: Well, actually, you don't need much exposure. You know, basically 20 to 30 minutes in the morning, when the brain is the most sensitive to light, does the trick.
FLATOW: And if it's working, you'll know it immediately?
FRIEDMAN: It's very fast. The treatment has an onset of action that's much faster than antidepressants.
FLATOW: And much cheaper. (Laughing)
FRIEDMAN: Much cheaper and less side effects.
FLATOW: And a lot less side effects. Why - is there some evolutionary advantage to this? Why would people have this happening?
FRIEDMAN: It's a fascinating question. Well, it seems like there might be. In the sense that, you know, people who have seasonal depression look like they're going through some sort of energy conservation strategy. They're eating less, they're conserving energy, they're more tired, they want to be a couch potato. They consume a lot of calories. They look like, in a sense, they're hibernating. Not hibernating in the way that bears hibernate, where their body temperature goes down.
And, in fact, there are very interesting scientific experiments that have been done looking at people who have seasonal depression and looking at the difference in their melatonin secretion during the winter compared to people that don't. And they behave like hibernating animals, because what happens is that as the daylight gets shorter, their nighttime get longer and their melatonin secretion gets longer in the winter. It's like hibernating animals.
FLATOW: Well, how do we know that we're not the abnormal people and they're the normal people?
FRIEDMAN: Well, in a sense, we might be the abnormal people in the sense that, you know, people that don't have seasonal depression have a constant melatonin secretion all year long, even though daylight is getting shorter, and probably because we're sensitive to artificial light. So with artificial light we've extended the day.
FLATOW: Are there people who actually go the opposite direction?
FRIEDMAN: You mean people who are depressed in the summer?
FRIEDMAN: Yes. They're a smaller group of people and, mostly, you find those people in the South and, for some reason in Asian countries. So there's a smaller - much smaller percent of seasonal depressives have summer, you know, depressions.
FLATOW: And now, I've heard of therapies that involve going to the beach instead. Why would going to the beach work?
FRIEDMAN: Well, for two reasons. One, it's very sunny.
FRIEDMAN: Two, it's very beautiful. And three, it's filled with negative ions.
FLATOW: The beach is?
FRIEDMAN: The beach is. Yes. Wet, damp places have an excess of negative charge and although it sounds like snake oil, actually there's good empirical evidence that negative ion generators can actually improve seasonal depression, just like phototherapy.
FLATOW: So you could get a negative ion generator?
FRIEDMAN: You could get a high-flow negative ion generator. Yeah.
FLATOW: I've heard about positive, negative ions for years, I've heard about...
FRIEDMAN: Well, you know, the folklore about these hot, dry winds that drive people mad?
FRIEDMAN: Well, there's actually some scientific basis behind it because these hot, dry winds like the Santa Ana and the Foehn and the Mistral are full of positive ions and they do drive people...
FLATOW: Because I've also heard that the way animals know that the weather is going to change or people - they start sniffing the air, that they're detecting, possibly, the ion change that's coming.
FRIEDMAN: Yeah, possibly.
FLATOW: Also. Is it easier to get the light box or the negative ion generator? Which is it...
FRIEDMAN: Probably easier at this point to get the light box, and maybe cheaper.
FLATOW: Is it? Yeah.
FRIEDMAN: I think so.
FLATOW: And you can build your own if you want.
FRIEDMAN: You could, although the issue is, you want to really be sure that you've got a filter that will take away as much UV light as possible because you don't want to harm your eyes.
FLATOW: Right. You know, people will say to you, why don't you just get out of bed and go jog someplace? You'll feel a lot better.
FRIEDMAN: Yes. Well, people who don't experience depression always say things like that. You pull yourself up by your own bootstraps. It's very hard.
FLATOW: Yeah. If you could get out of bed, you wouldn't be depressed.
FRIEDMAN: By definition.
FLATOW: By definition. Thank you very much for joining us today.
FRIEDMAN: My pleasure.
FLATOW: We're talking to Richard Friedman, professor of psychiatry at Weill Cornell Medical College here in New York. Transcript provided by NPR, Copyright NPR.