Can a SAD Lamp Really Make You Happy?

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Photo: Alice S. / BSIP

If you live somewhere that experiences all four seasons, your mood, like your skin, may be taking a beating right now. People love to complain about forced holiday gatherings, but the fact is they provide company and copious amounts of sugar at a time when you’d probably otherwise mope around the house unshowered, eating Cheetos and grumbling about how it’s dark at 5 p.m. Now that Christmas and New Year’s are long gone, we’re faced with the reality that there are two excruciating months to go until the official start of spring, when humans are known to smile just on account of the nice weather.

Some amount of slothing is perfectly normal in the winter, but if you feel like you want to hibernate more often than not, you might have seasonal depression, also known as seasonal affective disorder (SAD). It’s a subtype of major depression that’s marked by downshifts in mood and energy starting in the fall and lasting throughout winter, though, in rare cases, the symptoms happen in spring and summer.

If you’ve done even the slightest amount of Googling, you’ll notice that light therapy is a recommended treatment. You can buy a box without a prescription — but should you? Here’s what you should know about SAD lamps and treating your own winter blues.

The connection between light and SAD

Light-therapy boxes aren’t merely an expensive prop to help you fantasize that you’re on a beach vacay. The idea is that exposing yourself to bright light when you first wake up will give your internal clock an anchor, says Michael Terman, PhD, professor of clinical psychology and director of the Center for Light Treatment and Biological Rhythms at Columbia Presbyterian Medical Center.

As modern humans with adult obligations, we have relatively static sleep cycles, but since the solar cycle changes throughout the year, that often means waking up when it’s pitch black outside during the fall and winter. Terman says our bodies are programmed to sync our 24-hour schedules to the first light of day, which is part of why we want to sleep later in the winter — the sun isn’t up yet, so why should we be?

This mismatch between the solar cycle and our sleep cycle, “two timed events that together guide our behavior, alertness, and mood throughout the day,” can lead to depression, he says. But using a light-therapy box when you first wake up tells your brain to start its 24-hour cycle at that moment, effectively putting it back in spring-summer mode. No more mismatch, no more “meh” feeling. (Another theory is that reduced light in the fall and winter hampers the brain’s production of serotonin, a neurotransmitter that helps regulate mood.)

So just turning on a lamp every morning is all you have to do? Unfortunately, it’s more complicated than that. First, nearly half of people with SAD don’t see improvement from light therapy alone, according to the National Institute of Mental Health. Plus, light therapy requires a minimum of 30 minutes per day, every day, from the time symptoms start until the spring when you naturally begin to feel better, says Kelly J. Rohan, PhD, professor and director of clinical training in the department of psychological science at the University of Vermont. This could mean having to get up even earlier  unless you already spend half an hour each morning sitting down eating or reading  and keeping it up for as long as five months. “Is everyone really ready, willing, and able to commit to the logistics of implementing this treatment in the long term?”

Most people are not, at least according to Rohan’s latest study, which was published in the November issue of the American Journal of Psychiatry. The randomized clinical trial had a pool of 177 people with SAD treated for six weeks with either daily light therapy or twice-weekly cognitive-behavioral therapy tailored for SAD. (CBT is a psychotherapy method that teaches people to challenge problematic thought patterns so they can react in a more effective way.)

Rohan and her team followed up with people the next two winters. The CBT folks were done with treatment after the initial winter, but the light-therapy subjects would have to keep it up.

In winters one and two, both groups had similar reductions in SAD symptoms. But there was a marked difference in the third winter: People who did light therapy had a relapse rate of 46 percent versus 27 percent in the CBT group, and they had more severe symptoms, too.

Why? Because they stopped doing it. People had to return the boxes to the lab after the first winter for upkeep, like bulb replacement. Before winter two, they got letters saying they could come in to borrow a box, and listing specifications if they preferred to buy one. For winter three, the lab didn’t offer loaners, but Rohan did offer to write letters to people’s insurance companies arguing that they should be covered. Less than a third of subjects in this group reported any light therapy that winter. And thus the higher relapse rate.

Rohan says light therapy isn’t a preventive treatment, it’s more like a maintenance medication that you need to keep using. But there’s evidence that CBT might be preventative, not just for SAD but for other mood disorders — it has a certain “durability,” she says.

“Yes, CBT might cost more money than a light box in terms of copays, but if in 12 sessions you can get a treatment that keeps giving over time and you’ve learned something to fortify yourself against a recurrence, you have to consider that as a benefit in light of those costs.”

To be clear, this study outcome doesn’t mean Rohan is anti-light-therapy altogether — she just knows from experience that it’s not for everyone. “If you use light therapy and benefit and if you’re ready and willing to stick with that treatment over time, more power to you. That is a good outcome,” she says. “However, if you’re not willing to stick with it, you might want to consider other options because you’re wide open for a relapse unless you’re doing something else.”

But it can’t hurt, right?

Using a light-therapy box can have unpleasant side effects, which is why Rohan recommends using one only under supervision of a health professional who has experience treating circadian rhythm disorders with phototherapy (the field is called chronotherapeutics).

The annoying (though mostly benign) side effects can include headaches, eye strain, feeling wired, or even insomnia if you use the light too late in the day. Terman thinks the risk is minimal for people with only mild mood disturbances and says it might make sense for them to explore light therapy on their own. 

But for those with a history of clinical depression or bipolar disorder, he and Rohan agree: Definitely don’t try this at home. Not only can medications like antidepressants interact with light therapy and require dose adjustments, Terman says, but there’s a chance that you could have an exaggerated response, like deepened depression or hypomania. “That’s something the lay person probably wouldn’t be prepared to deal with if they experienced this on their own without some kind of supervision,” Rohan says.

For Rohan’s study, which included subjects taking antidepressants, her team closely monitored people’s use of the boxes. “We have to try to get the dose just right — how many minutes per day does this person need to use it, at what exact time, in order to get the best benefit while minimizing the side effects,” she says. “It’s not a one-size-fits-all prescription, it takes some trial and error.”

So what should I do?

Ultimately, it’s an individual decision. If you want to try therapy, Rohan says a therapist trained in CBT could easily learn how to do CBT for SAD with the manual for mental health professionals she published in 2008 with Oxford University Press. Rohan’s version of CBT focused on helping people identify and change negative thoughts associated with winter and getting them to do things they enjoy instead of isolating themselves. But yes, that might mean buying the $42 book off Amazon yourself and goading your therapist to read it. (Though you might persuade them that it’s good for business.)

If you’d prefer using a light-therapy box and you’re beyond Terman’s “mild disturbance” benchmark, ask your doctor or psychologist if they’d be comfortable supervising your treatment before you buy one. If they’re not, maybe they can recommend someone with a background in chronotherapeutics. And remember that you’re committing to using it daily.

Maybe neither option really appeals to you. In that case, you could try some of the things Rohan encourages in her SAD-focused CBT, like joining a book club or learning something new, like knitting. You can also try lifestyle shifts recommended to help reduce symptoms of both seasonal depression and major depression, like getting outside as much as possible, working out to relieve stress, and eating and sleeping well. And if you can actually swing a beach vacation, it certainly couldn’t hurt!