1. In healthy adult woman, does light therapy compared to a placebo impact
seasonal affective disorder?
Lynn Bucher, Nikki Schenandore, Taylor Folk, Jenn Hulse & Jill Johnson
York College of Pennsylvania
Introduction
METHODS
RESULTS Recommendations
SUMMARY
Seasonal Affective Disorder (SAD) affects 0.4%-
2.7% of the general populations of the United
States and Canada. SAD has been defined as a
mood disorder consisting of recurrent episodes
of depression that are congruent with a
“seasonal pattern.” Winter depression is the
most common type, and is manifested by
symptoms of depression during the fall and
winter seasons followed by a full remission in
spring and summer. Symptoms associated with
SAD include: Depressed mood; Lack of energy;
Hypersomnia; Carbohydrate craving with
subsequent weight gain. Impairment, in those
suffering from SAD, in the areas of occupational
and social functioning has also been identified.
The primary treatment for SAD is light therapy
which is exposing the sufferer to artificial bright
light during the symptomatic months.7 We chose
to explore the efficacy of light therapy as the
optimal treatment for SAD. Our PICO question
is: In healthy adult women, does light therapy,
compared to a placebo, impact Seasonal Affect
Disorder.
A total of 35 research articles were found and
reviewed using PubMed, Google Scholar, OVID,
and Chochrane databases. Of the 35 articles
found, 25 of them were excluded because they
did not have significant data, weren't
experimental, or did not meet the criteria for our
PICO question. The search terms that we used
included light therapy, seasonal affective disorder
(SAD), seasonal mood disorder, depression,
randomized controlled trial, placebo, or they were
references found in other research articles that
we reviewed. We limited our search to articles
that were written in 2001 and later.
• Since there are few studies testing light
therapy using a placebo condition, further
research is needed to create a placebo for
visible light treatment.5,8
• There is a need to test the effects of light
therapy based on a patient’s individual
circadian rhythm to determine the
appropriate time to administer the light
therapy, rather than just being
administered in the morning.1,7
• A strong design and methodology, by the
use of an inactive control group, can
reduce the occurrence of uncommon
events such as light sensitivity or sight
problems.1
• Standardizing treatment time can decrease
side effects and lead to more positive
outcomes.4
We conclude that light therapy compared to
placebo therapies (pharmalogical, cognitive,
negative ion, transcranial bright light) is an
effective treatment for healthy adult women
suffering from seasonal affective disorder. A
minimum of four weeks of bright light treatment
has been proved to significantly decrease
depressive symptoms associated with seasonal
affective disorder when compared to other
placebos.
EVIDENCE SUMMARY TABLE
Level of
Evidence
# of
Studies
Summary of Findings Quality
Level I:
Experimental
(randomized
controlled
trial- RCT) or
meta-
analysis of
RCTs
7
 Early morning light exposure resulted in greater
remission of SAD symptoms based on the SIGH-
SAD, compared to a placebo.1
 With 4 weeks of light therapy treatment,
patients experienced a significant decrease in
depressive symptoms and higher rates of
remission.3
 Patients receiving Bright White light therapy
showed significant decreases in SAD symptoms
according to the SIGH-SAD scale.4
 Effects of bright light therapy are comparable to
effects found in many antidepressant
pharmacotherapy with a significant reduction in
symptoms of depression.5
 Although bright light therapy improves
symptoms in the first week of treatment, there
was no significant difference between light
therapy and antidepressant therapy after 6
weeks.7
 Ten-day bright light treatment in a light therapy
room reduced self-reported depression in
subjects with winter depressive mood.9
 Light therapy combined with cognitive-
behavioral therapy may be the most optimal
treatment for SAD.10
B1
B3
A4
B5
B7
B9
C10
Level II:
Quasi
Experimental
3
 Bright light in the workplace is effective in
improving mood, energy, alertness, productivity,
and the quality of awakening. 2
 After receiving transcranial bright light therapy
for 4 weeks, patients experienced a significant
decrease in depression and anxiety related to
SAD on both a self-rated and psychiatrist rated
scale.6
 Low-intensity blue white light is highly effective
and equal to standard bright light in improving
symptoms of mood, sleep quality, and energy
levels.8
C2
B6
B8