From: altar@beaufort.sfu.ca (Ted Wayn Altar)
Subject: Re: Vitamin D from sunshine
Organization: Simon Fraser University, Burnaby, B.C., Canada
Date: Mon, 4 Jan 1993 09:38:15 GMT

Clover M. writes:

>Actually, I appreciate all of the feedback on the lights and vitamin D.
>But what I am looking for is information on the lights that are used
>in SAD therapy, which I suspect I may have.

Clover, I am a bit uneasy about making any loose and fast recommendations
regarding light therapy for SAD, at least not without some backgound
information and qualification.  Forgive me if I am only explaining some
things you already know, but other readers might not be as well versed
in knowing about SAD and light therapy.


WHAT IS SEASONAL AFFECTIVE DISORDER (SAD)?

    While there is still some controversy about whether seasonal
affective disorder (SAD) deserves to be treated as a separate
sub-class of recurrent mood disorders, it has been distinguished
as a recurrent mood disorder in which there is (1) a regular
temporal relationship of bipolar or major depression within a 60
day period of the year (2) full remission occurs with a 60 day
period of the year (3) at least 3 episodes in 3 years and no less
than in two consecutive years (4) episodes of seasonal mood
disorder outnumbers non-seasonal mood disorder by 3 to 1.

The usual picture therefore involves recurring episodes of
depression, mania or hypomania during certain seasons.  The most
common pattern is a fall-winter depression alternating with non-
depressed periods during spring-summer and with no other factors
accounting these mood changes.  The second most common pattern
consists depression occurring in the summer rather than in the
winter.  Needless to say, phototherapy is not effective for
summer SAD.

While SAD has been most frequently diagnosed among women in their
early 30s (depending on the sample and diagnostic criterion, this
figure has been put as low as 22), one cannot preclude the social
possibility of men simply being less inclined to report symptoms
and seek therapy.

It should be remembered that affective disorders (like
depression) are commonly precipitated by any number of psycho-
social stressors and environmental conditions.  For instance,
there is peak incidence largely in the Spring, at different latitudes 
and in different continents.  Societal factors are even more
complicated (and are quite seasonally constant in present day
urban societies).  While biological and climatic factors are
pertinent, research does not yet give credence to a photogenic
theory of this disorder.  This is not to say that seasonal light
doesn't help and can't be an effective treatment, but only to
suggest that one should not ignore other treatments and psycho-
social life considerations underlying one's possible SAD.  Hence,
it is always a good idea to get a professional diagnosis before
investing in what might be a considerable monetary investment in 
the kinds of bright light usually used for phototherapy.

Aside from the profound disturbance in mood, persons afflicted
with SAD often show hypersomnia (uncontrollable sleepiness), and
carbohydrate craving.  Also, irritability and increased appetite
tend to be more common with SAD suffers than with nonseasonal
depressions.  Other symptoms, however, like depression, insomnia,
appetite loss, fatigue, anxiety, difficulty in concentration and
dysphoria are equally common among SAD sufferers as it is with
recurrent nonseasonal depressions.

With an appetite increase many SAD sufferers often report a
weight increase (about two thirds of sufferers).  Of course, almost 
everyone has a tendency to eat and sleep more and to gain weight 
in the winter, and this should not be confused with SAD.  To blur
matters even more, not all studies report a weight or body mass
change of SAD sufferers taken as a whole.  This may be because
SAD sufferers also tend to have a higher resting metabolic rate
than normals!


HOW EFFECTIVE IS PHOTOTHERAPY

Studies have shown phototherapy effective for some SAD sufferers.
Based on the Hamilton Rating Scale for Depression for SAD, one
small study (Haruo & Mitsuo, 1991) of 25 SAD sufferers showed the
following improvement:

    65% of sufferers showed a scale improvement of  >50%
    24% "     "        "    "   "         "      "  25-50%
    14% "     "        "    "   "         "      "  <25%

Hence, while effective in giving improvement to many sufferers,
it is not an effective treatment for 14% or 25% (depending on
one's criterion of "practical" improvement as indexed by our 
Hamilton rating scale).  

While it might seem like putting the cart before the horse, it 
has been suggested that one way to define SAD from, say atypical 
depression, is by its responsiveness to phototherapy.

While the PLACEBO EFFECT has maybe not been adequately resolved,
studies were full spectrum light is markedly more effective than
equally photon intense red light treatment does suggest that more
than a placebo effect accounts for the improvement.  Still, we
can't rule it out just yet.

People with no history of winter difficulties or current
depressive symptoms do not appear to profit in mood from phototherapy
This kind of differential treatment outcome would suggest that
SAD is a distinct problem from atypical or recurrent mood
disorder.  The degree hypersomnia of SAD sufferers is the
particular symptom most predictive of a lessening of depression
after phototherapy.


PHOTOTHERAPY: HOW MUCH AND HOW LONG?

The beneficial effect of light does appear to depend on the
duration of exposure.  While as little as 2 hours can incur an
improvement, 5 hours will generally be more effective than 2 hrs,
but maybe not enough to warrant what might be a person's
practical constraints for such long durations .

Bright light (usually about 2500 lux full spectrum fluorescent
light) works better than dim light (300 lux), although even with
dim light some studies report improvement.  Most studies,
however, show a better improvement with the bright lights,
particularly with respect to a persistence of relief after light 
treatment is stopped.

To help illuminate (pun intended) what is these "lux" numbers
mean, the guidelines for indoor lumination set the required
brightness level at somewhere between 200 and 1000 lux, which is
around twilight level.  Midday sunlight, even through a cloud, is
about 10 times brighter than this.  People on average are only
infrequently exposed to anything over 1000 lux.  Indeed, one
study in sunny San Diego reported that their volunteer subjects
wearing light detectors on their wrists appeared to spend most of
their waking hours in light of an average intensity of about 100
lux!  Do we still live in the dark ages?  :-(

Thus, 2500 lux is VERY bright light by indoor standards, which
means that a SAD sufferer must sit quite close to some very
strong full spectrum lights (after all, their is the inverse square
law to contend with, so that being 3 feet away reduces the light
intensity by 9 fold).  Home treatment for a SAD sufferer might
require them to sit as close as 1 foot away, with their eyes open
but not looking directly into the light.

In general 2,500-lux intensity light exposure for at least 1-2
hrs daily for 1-2 wks will result in measurable improvement.
Some treatments have used white light of intensities as high
as 10,000 lux!  Ouch, my eyes.  Others, however, have found that
even dim yellow light of 300-lux will have beneficial results,
but again, more consistent results of improvement between studies
are obtained with the bright light (minimum intensity of 1500
lux).

While morning exposure seems to be better, evening exposure is
almost if not just as effective.  Midday treatments tend to be
less effective than either early morning or evening treatments.
Dual exposures (morning-plus-evening) does not always provide any
greater benefit than morning light alone.

Full-spectrum white light works better than either blue or red
light.  One study showed that when ultra violet was added, as compared
to being blocked, the resulting phototherapy gave an improvement on
some scales (e.g. Atypical Symptom Score) but not all (like the
Hamilton rating or Beck depression scale), which may account for the
inconsistent findings on the efficacy of increasing the spectrum
of white light to include ultra-violet.  One *might* here suggest
the UV-spectrum in light therapy may have a differential effect
on atypical symptoms in SAD.  In sum, whether or not ultra-violet 
is included is not really necessary.  More important is that simply 
bright white light be used.

                                     Hope this helps,
                                          ted


REFERENCES:

Wirz-Justice, Anna et al. (1986).  How much light is
    antidepressant?  PSYCHIATRY RESEARCH, 17(1):75-76

Eastwood, M. R. ; Peter, A. M. (1988).  Epidemiology and Seasonal
    Affective Disorder.  PSYCHOLOGICAL MEDICINE, 18(4): 799-806

Isaacs, Geoffrey ; Stainer, D. S. (1988).  Phototherapy and its
    mechanisms of action in seasonal affective disorder.  JOURNAL
    OF AFFECTIVE DISORDERS, 14(1):13-19

Rosenthal, Norman E. ; Genhart, Michael   Disturbances of
    appetite and weight regulation in seasonal affective
    disorder.  ANNALS OF THE NEW YORK ACADEMY OF SCIENCES, 1987,
    499:216-230

Rosenthal, Norman E. et al. (1985).  Seasonal affective disorder
    and phototherapy. ANNALS OF THE NEW YORK ACADEMY OF SCIENCES,
    453:260-269


Murray, John B. (1989).  Geophysical variables and behavior:
    LVII. Seasonal affective disorder and phototherapy.
    PSYCHOLOGICAL REPORTS, 64(3, Pt 1):787-801
Okudaira, N. et al. (1983).  Naturalistic studies of human light
    exposure.  AMERCIAN JOURNAL OF PHYSIOLOGY, 245:R613-R615.

Winton, F. ; Corn, T. (1989).  Effects of light treatment upon
    mood and melatonin in patients with seasonal affective
    disorder.  Psychological Medicine, 19(3):585-590

Stinson, Deborah & Thompson, Christopher (1990).  Clinical
    experience with phototherapy.  JOURNAL OF AFFECTIVE
    DISORDERS, 18(2):129-135


Doghramji, Karl ; Gaddy, James R. (1990).  2- versus 4-hour
    evening phototherapy of seasonal affective disorder.  JOURNAL
    OF NERVOUS & MENTAL DISEASE, 178(4):257-260

Stewart, Jonathan W. ; Quitkin, Frederic M. (1990).  Is seasonal
    affective disorder a variant of atypical depression?
    Differential response to light therapy.  PSYCHIATRY RESEARCH,
    33(2):121-128

Nagayama, Haruo ; Sasaki, Mitsuo (1991).  Atypical depressive
    symptoms possibly predict responsiveness to phototherapy in
    seasonal affective disorder. JOURNAL OF AFFECTIVE DISORDERS,
    23(4):185-189