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11/07/2007
Don't be Sad, Turn on the Light
Last week, we discussed the benefits of exposure to sunlight to
ensure the production of vitamin D. Of course, overexposure to
the sun’s rays can lead to burning and possibly skin cancer. For
some people, a lack of sunlight can pose a different problem. I
was catching up with my unread issues of Science when,
perusing the September 14 issue, I was startled to find a former
colleague at Bell Labs the focus of a news article by Yudhijit
Bhattacharjee titled “Is Internal Timing Key to Mental Health?”
The first sentence in the article: “Every year, after the colors of
autumn faded from the trees and left barren branches to herald
the winter, Herbert Kern would feel his mental skies darken.” I
may have mentioned Herb Kern in a column some years ago.
Herb was a very pleasant chap and I distinctly remember being
surprised when one day back in the 1980s he told me of an
unusual medical problem he had. As the Science article relates,
when winter approached and days became shorter, Herb’s mental
outlook would change. He became depressed, minimizing his
social contacts and his productivity at work declined
precipitously. This happened every year in the 1970s. Late in
that decade, Kern learned about animal studies showing that
melatonin plays a role in the control of seasonal behaviors such
as mating. It was known that the production of melatonin was
influenced by the light-dark cycle of day and night. Kern
wondered if melatonin might be responsible for his own seasonal
problem. Herb described to me how he got in touch with a
researcher who was an expert on the effects of melatonin and
how that contact changed his life.
The researcher was Alfred Lewy at the National Institute of
Mental Health (NIMH) in Bethesda, Maryland. In December of
1980, Kern was in depression and the NIMH team led by Lewy
and his colleague Thomas Wehr decided to try to mimic the
amount of light that one would normally get on a sunny spring
day. They did this by exposing Kern to artificial light for a
number of hours in the early morning and in the evening. A few
days of this treatment brought about a drastic change. Herb said
that he felt “bubbly” again. When he returned home to New
Jersey he continued the light regimen, which worked like a
charm. No more depression.
Kern’s case and a few years of follow-up work by researchers led
to the conclusion that this winter depression was a real
psychiatric illness; it became known as SAD, seasonal affective
disorder. This linking of a real disease with a disruption of the
normal 24-hour biological clock cycle, the so-called circadian
rhythm, spurred further research on SAD. There may be millions
of people affected to varying degrees with this disorder. I know
personally one other individual with a serious case of SAD. This
person also responded positively to treatment with periods of
artificial light.
What is it that lengthening the effective daylight hours does that
promotes the lifting of the depression? After more than 35 years,
the answer still isn’t nailed down. Over the years, researchers
Lewy and Wehr came to believe in two opposing explanations.
Lewy believes in a “phase-shift” hypothesis that posits that SAD
results from what amounts to a chronic type of jet lag in which
the biological clock is out of sync with the normal sleep-wake
cycle. When the clock is reset back in sync, the patient feels
better. Wehr feels that the lengthening of the number of daylight
hours suppresses the amount of melatonin produced in the body
and that it’s the decreased levels of melatonin that lead to the
patient’s improved mood.
Melatonin is a compound that has gotten a good deal of media
attention as a sleep-inducing agent and as something that may be
helpful in adjusting to jet lag. (I hasten to add that I am not an
MD and certainly am not pushing the use of melatonin for
anything!) The body apparently starts to produce melatonin a
couple of hours prior to bedtime as a precursor to a good night’s
sleep. Other than melatonin, there are a number of other
hormones that are produced in conjunction with the light-dark
circadian rhythm. One is serotonin, known as a sort of feel-good
compound that promotes a feeling of well being. Sunlight has
been shown to promote increased levels of serotonin in the brain
while it promotes a decrease in melatonin production.
Lewy, now at Oregon Health and Science University, and his
colleagues reported last year on experiments with melatonin pills
given either in the morning or in the afternoon in attempts to
duplicate the effects of the artificial light treatments. Some of
the subject’s biological clocks were out of sync lagging their
sleep-wake cycles while other subjects’ clocks were out of sync
in the opposite direction. The laggards felt better taking the
afternoon melatonin pills, which apparently pushed these
patients’ clocks back in sync. The other group felt better with
the morning pills, which brought them back in sync from the
other direction. While these experiments seemed to favor
Lewy’s phase-shift proposal, Wehr and others suggest that to
really settle the question would require continuous monitoring of
the melatonin levels over full 24-hour periods. The question as
to the levels and effects of other hormones, such as serotonin,
also remains up in the air.
The Science article also cites work suggesting that troubles with
the circadian rhythms may be involved in other mental disorders
such as bipolar disorder and certain obsessive-compulsive
disorders. In animal studies at the University of Texas
Southwestern Medical center in Dallas, the removal of the so-
called Clock gene in mice leads to manic hyperactive behavior.
The Clock gene is associated with production of a protein that is
a key protein involved in the mice’s circadian rhythms.
Indications of defective biological clocks in human bipolar and
schizophrenic patients have been reported in studies from the
University of Pittsburgh Medical Center and from the Psychiatric
University Clinic in Basel, Switzerland.
As for Herb Kern, I was happy to read that he’s still alive.
However, he’s suffering from macular degeneration and is nearly
blind. Over the years the light therapy became less and less
effective as his eyesight failed. Now, his biological clock seems
to be running without any input from his environment and he’s
suffered from periods of depression and “highs” lasting a year or
more. The Science article quotes him as saying, cheerfully,
“Now I can hardly see, and all hell has broken loose.” It’s good
to hear that Herb still retains a sense of humor. I suspect that his
decreasing response to the light therapy with his advancing
blindness represents more data for researchers. Herb’s still
contributing to science.
Finally, after last week’s column on the very impressive benefits
of vitamin D, there was a brief news article in the Star-Ledger
about a recent study questioning whether vitamin D prevents
certain cancers. Next week, I’ll try to follow up.
Allen F. Bortrum
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