Seasonal Affective Disorder
Life Extensions (2015)
Many people may feel sad or down during the winter months, when the days are shorter
and temperatures drop. For some people, this condition goes beyond the winter “blahs” and
develops into a subtype of clinical depression that lasts throughout the late fall and winter
months. This condition is known as seasonal affective disorder, or SAD. The term SAD was
introduced in 1984 and has since been included in the American Psychiatric Association’s
Diagnostic and Statistical Manual of Mental Disorders.
SAD is characterized by recurring, cyclic bouts of depression, increased appetite, and an
increased need for sleep (Ford 1992; Magnusson 2003). It contrasts with most depressive
disorders, which are characterized by sleep disturbances and diminished appetite (Magnusson
2005). Besides mild depression, typical symptoms of SAD include anxiety, decreased activity,
social withdrawal, increased sleep duration, increased appetite, weight gain, and carbohydrate
craving (Rosenthal 1984; Sher 2001).
SAD occurs in about 10% of the general population, although it is about twice as
common among people treated for depression (Gross 1996). It tends to be more common in the
higher latitudes, where winter days are comparatively shorter than at latitudes nearer the equator,
and it occurs more often in women than in men (Rosen 1990; Gross 1996; Magnusson 2003)…
What Causes SAD?
The 24-hour sleep-wake cycle, known as the circadian rhythm, is governed in part by the regular
rise and fall of hormones, especially melatonin. Melatonin, the master sleep hormone, is
produced in the pineal gland. Researchers have identified a regular ebb and flow to human
physiology and behavior throughout a normal 24-hour cycle (Hirota 2004). Our overall pattern of
sleep-wake depends on the proper functioning of an internal circadian clock, which lies deep in
the brain. This circadian clock works with photosensors in the eyes to sense darkness. When
darkness falls, the body begins to secrete melatonin, which is one of the factors that cause sleep.
Melatonin continues to be secreted throughout the night, although levels alter, and toward dawn,
melatonin secretion gradually diminishes, allowing for wakefulness in the morning.
When there is a problem with this system, sleep disorders and other psychological problems can
occur. Recent research has identified a number of possible abnormalities that may help explain
and offer therapeutic targets for SAD.
The Melatonin Theory. Early research focused on the shorter photoperiod in winter,
hypothesizing that shorter days led directly to SAD. Researchers initially attempted, with some
success, to lengthen the photoperiod by exposing individuals to bright light in the morning and
evening (Rosenthal 1984; Winton 1989). Next, researchers focused on the secretion of
melatonin, which controls the sleep-wake cycle.
Although the 24-hour rhythm of melatonin secretion is generally the same in SAD patients and
controls during winter months, researchers hypothesized that people with SAD had increased
duration of melatonin secretion in the early morning hours (Checkley 1993; Partonen 1996). This
would explain why people with SAD have difficulty waking up and do not feel alert in the
morning. Experiments with drugs to block melatonin secretion in the morning, thus decreasing
the duration of its secretion, found the symptoms of SAD were relieved (Schlager 1994).
Conventional Treatment of SAD
First-line treatment for SAD is light therapy. During light therapy, patients are exposed to bright
light early in the morning in an attempt to reduce the secretion of melatonin and stimulate a more
natural waking cycle. Studies of patients with SAD indicate that bright light therapy in the
morning produces greater therapeutic effect than evening light (Eastman 1998; Lewy 1998b).
Study to Support Melatonin’s Link to SAD
Avery et al (2001)
 Aim: To understand the role of light, Melatonin, and SAD
 Procedure: Assigned 95 SAD patients to three different groups
 1. Received dawn stimulation starting at 4:30 AM
 2. Received traditional bright light therapy (exposed to a bright light as soon as
they woke up)
 3. Placebo received exposure to red light at dawn
 Findings:
 Those who had been exposed to the placebo or bright light showed less
improvement in their SAD symptoms. The Placebo patients reported having
insomnia.
 Conclusion:
 Symptoms of SAD are related to sleep patterns.
 In the winter, we wake before the sun rises.
 In darkness, our Melatonin rises, which helps us fall asleep.
 When we rise and it is still dark outside, our Melatonin levels remain high, which
causes the symptoms of SAD (feeling lethargic, feeling tired, non-motivated)
 Bright light therapy and dawn therapy both helped to elevate these symptoms, but
the dawn simulation had less side-effects (including headaches and nausea)
Name:_______________________________________
Block:_______
Dawn Simulation and Bright Light in the Treatment of SAD: A
Controlled Study Questions
Directions: Read the article, and then answer the questions which follow
Background: Seasonal Affective Disorder (SAD) is a depressive disorder which is seasonal. People who
are diagnosed with SAD experience depression symptoms in the winter months. The hormone
melatonin has been linked to causing depression. Melatonin is the hormone responsible for helping
you fall asleep, the production is stimulated by a dark environment. Melatonin is the hormone
responsible for making you feel drowsy and lethargic. During the winter months, there are longer
periods of darkness. This darkness spurs a greater production of melatonin, which in turn makes
people feel lethargic and at times depressed.
1.
What three groups were participants placed into for this study?
2. What were the results of the study?
3. What are two advantages of using Dawn Simulation Therapy over Bright Light Therapy? (What
are two symptoms of Bright Light Therapy)
4. Which therapy is more effective, Dawn Simulation or Bright Light? How do you know?
5. What ethical considerations were taken when performing this study?
6. Why are people more likely to develop SAD in the winter months?
7. In a 1-2 page paper (font 12, Times New Roman, double spaced) discuss how the environment
may affect physiology.