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Seasonal Affective Disorder
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By Claudine Chamberlain
Oct. 14
— Back in the early 1980s, a handful of experts at the National
Institute of Mental Health had a wild idea: If people get depressed
when the days get darker, why not just give them more light?
They tested their theory on Herb Kern, a
63-year-old research engineer who fell into a deep blue funk every fall.
They built a 2-foot by 4-foot metal box, inserted bright fluorescent
bulbs, covered it with a plastic screen and asked Kern to sit in front
of it for three hours before dawn and three hours after sunset every
day.
It worked. Three days later, Kern was smiling
again. In the 15 years since then, further studies have shown the
effectiveness of light therapy—using brighter lights and shorter
treatment times—for patients with winter depression, known medically
as seasonal affective disorder or SAD. An estimated 10 million Americans
have SAD.
But questions remained: How, exactly, does
light therapy work? Is it scientifically valid? Should people with SAD
be “lit” in the morning or evening?
Read it and (Don’t)
Weep
Three studies published today in the Archives of General Psychiatry
answer some of those questions. And together with two enthusiastic
editorials, the studies push light therapy solidly into the mental
health mainstream.
“Light is as effective as drugs, perhaps more
so,” writes Anna Wirz-Justice of the Psychiatric University Clinic in
Basel, Switzerland. The three studies “provide the best evidence to
date.”
Some psychiatry purists have sniffed that light
therapy is “merely a placebo response by mildly neurotic middle-aged
women who don’t like nasty drugs,” says Wirz-Justice. But now
there’s proof enough for skeptics that light therapy is for real.
Advocates expect that this week’s news will
convince even more mental health therapists to use bright lights for
their depressed patients, and may convince more insurance companies to
cover the roughly $300 cost of the light boxes.
Springtime in December
For one of the studies, Charmane Eastman, a psychologist at
Rush-Presbyterian-St. Luke’s Medical Center in Chicago, tested 96 SAD
patients. She found that 61 percent of people who got morning light
therapy and 50 percent of people who got evening light therapy
experienced nearly complete recovery from their seasonal depression
after four weeks of treatment.
Only 32 percent of people who got a placebo
treatment enjoyed that same degree of remission.
What makes Eastman’s study so remarkable is
what she used as her placebo, or dummy treatment. Other studies have
used dimmer light boxes, or boxes that emitted different colored lights.
But patients who didn’t get the bright white light could clearly see
that they weren’t getting the good stuff, and skeptics said that
discouragement might have been the reason they didn’t respond well.
Eastman, however, used a negative ion generator
as the placebo. Adding invisible negative ions to the air might actually
fight winter depression (because summer air contains more negative
ions), so patients found the treatment believable. But Eastman
deactivated the device, adding a humming noise that made it seem like it
was working when it was turned on.
So, even though patients fully expected the
sham treatment might help them, and did get some relief from their
depression, they didn’t recover as completely as patients who got
bright light. And that means that light therapy must have some kind of
actual biological effect.
Skeptic Turns Believer
Ironically, Eastman herself had been considered a skeptic because her
earlier experiments showed that light therapy didn’t work any better
than a placebo. “There was a little black cloud of doubt” hanging
over light therapy, she says. “I’m sure people are saying, ‘If she
believes it now, it’s got to be true.’”
A second study provided similar findings. Dr.
Michael Terman, a psychiatrist at Columbia University in New York,
compared light therapy to treatment with high- or low-density negative
ion emitters. (His ion machines were working.) He found that
light-therapy patients did 30 percent better than those who got the
low-density ions. Patients who got high-density ions did just as well as
light-therapy patients, indicating that the high-dose ions might also be
helpful in treating SAD.
The third study, by Dr. Alfred Lewy of Oregon
Health Sciences University in Portland, compared the effectiveness of
light therapy given in the morning or the evening. He found morning
therapy at least twice as effective as evening therapy.
Taken together, these studies offer a 1-2-3
punch in favor of light therapy, at least for winter depression. It’s
less costly than antidepressant drugs, patients like it and the side
effects are relatively mild. Now, researchers say, it’s time to start
testing light therapy on other conditions, like jet lag, premenstrual
syndrome, nonseasonal depression and sleep disorders.
Why Winter Makes Us SAD
Think of
winter depression as four months of jet lag.
The human body has hundreds of 24-hour
biological rhythms (called circadian rhythms), all controlled by one
“internal clock.” The sleep cycle is one rhythm. Body temperature
is another. The brain’s production of certain chemicals, like the
nighttime hormone melatonin, is another.
In the summer, we wake up with the sun and go
to bed when it gets dark, so our body’s internal clock is in synch
with the sun. But in the winter, most of us force ourselves to wake up
while it’s still dark. And that means that the sleep-wake circadian
rhythm is out of step with the other rhythms, which we can’t control
with an alarm clock.
Scientists suspect that light therapy helps
fight winter depression because it kicks the other biological
rhythms,
namely melatonin, into step with our artificially manipulated sleep
cycle.
A study by Dr. Alfred Lewy, of Oregon Health
Sciences University in Portland, supports that theory because it showed
that morning light is more effective than evening light. Bright lights
suppress the brain’s secretion of melatonin. In other words, your
hormones want you to stay sleeping, but the light convinces them that
it’s time to wake up.
For roughly 80 percent of SAD patients,
melatonin levels peak just when it’s time to wake up. For them,
morning light therapy is best. For others, melatonin drops too soon, and
they find themselves waking up in the middle of the night. For those
patients, evening light therapy might work better.
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Why Winter Makes Us SAD
Think
of winter depression as four months of jet lag.
The human body has hundreds of
24-hour biological rhythms (called circadian rhythms), all
controlled by one “internal clock.” The sleep cycle is one
rhythm. Body temperature is another. The brain’s production
of certain chemicals, like the nighttime hormone melatonin, is
another.
In the summer, we wake up with the
sun and go to bed when it gets dark, so our body’s internal
clock is in synch with the sun. But in the winter, most of us
force ourselves to wake up while it’s still dark. And that
means that the sleep-wake circadian rhythm is out of step with
the other rhythms, which we can’t control with an alarm
clock.
Scientists suspect that light therapy
helps fight winter depression because it kicks the other
biological 
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rhythms,
namely melatonin, into step with our artificially manipulated
sleep cycle.
A study by Dr. Alfred Lewy, of Oregon
Health Sciences University in Portland, supports that theory
because it showed that morning light is more effective than
evening light. Bright lights suppress the brain’s secretion of
melatonin. In other words, your hormones want you to stay
sleeping, but the light convinces them that it’s time to wake
up.
For roughly 80 percent of SAD patients,
melatonin levels peak just when it’s time to wake up. For
them, morning light therapy is best. For others, melatonin drops
too soon, and they find themselves waking up in the middle of
the night. For those patients, evening light therapy might work
better.
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