The biggest evidence of the role of seasonal changes in human physiology and behavior is the observation of seasonal changes in birth rates, criminal behavior, suicides, children's growth and development, the levels of many hormones such as cortisol and testosterone, pain threshold, sexual activity and pregnancy rates. In normal people, weight differences and thyroid function changes can be observed depending on the seasons.
Most people start to feel more stagnant and unhappy with the colder weather, shorter days and dark cloudy weather. In the last 2 years, we have been hearing more and more people complaining about not having enough sleep because they feel like they have to get up in the middle of the night and go to work, especially since winter time is not applied. Seasonal Affective Disorder, commonly known as winter depression, usually begins in October-November, worsens in January-February, and continues until the winter ends.
Seasonal Affective Disorder was first described by Rosenthal et al. in 1984. Dr. After Norman Rosenthal moved from South Africa to the United States, he noticed that while he felt less productive in the winter months, this situation returned to normal in the spring. At that time, he worked with Al Lewy and Tom Wehr, who were investigating the effect of the melatonin hormone and suppressed light on circadian rhythm; have proven that bright light is effective in the treatment of patients with MDD.
Seasonally Patterned Affective Disorder (MDD) is a distinct form of Recurrent Major Depression or Bipolar Disorder. MDD is defined as having at least one type of episode (mania, hypomania, or depression) starting and ending at the same time of year for at least two consecutive years. During these two years, such a period is not experienced in any other season, and seasonal complaints are predominantly seen throughout the person's life. Other types of periods may not show a seasonal pattern.
For example, a person with seasonal bipolar disorder experiences seasons of depression that begin every December, but their mania/hypomania may occur irregularly at any time of the year. Or, a person with seasonal Recurrent Major Depression experiences seasonal depression only in winter, but not in winter. has no complaints. Although depression in MDD is often seen in winter months; Depression may be experienced at the beginning of the summer months.
How often and in whom does it occur?
Research shows that depression is reported to primary health care institutions for various reasons. It was revealed that 29% of the patients who applied had problems due to seasonal changes without experiencing depression. MDD is seen with a frequency of 5 - 6% in the society. In different patient groups with depression, SAD was found as follows: 81% in BP II, 7% in BP I, 12% in UP. Seasonal pattern is seen in 12% of recurrent depression, 12% of Bipolar Disorder type I, and 81% of Bipolar Disorder type II. As can be seen, type II, which is one of the subtypes of Bipolar disorder with hypomania, is much more common than type I. Its incidence increases as you move away from the equator in the northern and southern extremes. Depression is more common in young people and women during the winter. Familial factors may also play a role in the development of MDD. Rosenthal found a rate of mood disorder in 69% of first-degree relatives of his patients and MDD in 17%.
What are the symptoms?
In MDD, mood and cognitive changes typical of major depression are usually observed, such as sad mood, reluctance, fatigue, withdrawal, decrease in daily activities, and difficulty in concentration. However, unlike normal depression, irritability and difficulties in interpersonal relationships, sleeping more than normal, slowness, increased appetite and overeating, addiction to carbohydrate foods and, accordingly, weight gain are encountered. Although suicidal thoughts and attempts may occur in MDD, as in all other depressive disorders, depression in MDD is generally mild and moderate. Studies have reported that depression in 11% of patients requires hospitalization and electroconvulsive therapy (electroshock therapy) is required in 2% of patients.
Some people do not have complaints at a level that can be diagnosed with MDD. A patient who has only sad mood or only atypical somatic symptoms related to appetite and sleep and no other depressive complaints. rub has also been mentioned in studies. This condition has been called “subthreshold MDD.” Subthreshold MDD has been reported to be three times more common than the fully defined form.
Why does Seasonal Affective Disorder occur? What are the theories that explain it?
As can be seen from the examples, depressions, regardless of unipolar or bipolar, are generally seen in autumn and winter, while mania or hypomania are seen in spring and summer. In winter, the days get shorter, the sunlight decreases, and people stay indoors all the time, which negatively affects their psychology. But MDD is more than just 'winter boredom' or 'indoor boredom'. Due to seasonal association, the triggering of MDD is focused on the duration and intensity of daylight exposure in summer and winter, the amount and duration of melatonin hormone release during the day and night, circadian rhythm, and synchronization between sleep and wakefulness.
Autumn and winter. Not being able to benefit from enough daylight during the seasons causes a decrease in the serotonin level, which causes an increase in the melatonin level. The meletonin hormone in question has a natural sedative feature that slows down human physical movements and creates a sleepy and calm mood. Long-term release of melatonin initiates the energy storage process in the organism, leading to more sleep and food intake. This is the reason why we need more sleep and high-calorie foods during the winter months. Studies have shown that patients with seasonal depression have higher melatonin release during the daytime during the winter months and that the release phase of the melatonin hormone is delayed in 70% of the patients.
In people with depression, there are abnormalities in the initiation, termination and duration of melatonin release and in total melatonin levels. It has been observed that even healthy people sleep more than 9 hours and wake up 3 hours late in the morning, and their melatonin release at night is delayed. In the same study, when people returned to normal waking hours and limited their sleep to 6 hours, the melatonin release phase returned to normal. sleep with sleep It is obvious how important clock hours and daylight are in the circadian rhythm.
Circadian rhythm, which we can also call the body's biological internal clock, is regulated by stimuli such as light and darkness during the day and regulates the body's reaction mechanism in response to external stimuli. Circadian rhythm is triggered by the intensity and duration of light perceived by the retina layer in our eyes. Thus, in this rhythm; A reactive reaction occurs, including prolactin, cortisol, immune system, body temperature, cognitive functions, sleep-wake cycle and rhythmic release of melatonin. It is suggested that the circadian cycle is also responsible for our body's adaptation mechanism to seasonal changes.
There are three types of light-sensitive cells in the retina of our eye, called rod, cone and ganglion, which detect light. One of these, retinal ganglion cells, is sensitive to the intensity and duration of light in the environment, thanks to the melanopsin protein they have. Retinal ganglion cells containing the melanopsin protein do not respond much to sudden changes, so they do not play a role in vision. However, they mostly give feedback to our brain about the intensity and duration of light in the environment and are thought to be responsible for circadian rhythm in this way. In the presence of intense and prolonged light, the release of the melatonin hormone is suppressed and delayed.
Recent studies have found findings that the sensitivity of the retinal layer of the eye to light may be reduced in people with seasonal affective disorder. It has been determined that people who carry two mutated copies of the gene responsible for the production of the melanopsin protein are 5.6 times more likely to develop Seasonal Affective Disorder. It has also been determined that healthy people with this gene mutation go to bed earlier in the seasons when the days are shorter, and later in the seasons when the days are longer.
Studies have found that one or more genetic factors provide susceptibility or protection to MDD. It has been found that natives of northern countries have more genetic protection against MDD than those who immigrated there later. Apart from this, twin studies have shown a genetic predisposition to MDD. It revealed that the incidence is 29%.
What is the treatment for Seasonal Affective Disorder?
Antidepressants and antidepressants are used in the treatment of Seasonal Affective Disorder. In addition to vitamin D supplementation, light therapy (phototherapy)and cognitive behavioral therapy are also used.
People with seasonal affective disorder often report feeling great when they travel to a place with a sunny climate. However, travel is not always possible. Light therapy has been used for many years to treat seasonal affective disorder. It is as effective as antidepressant drug treatments and is considered the first choice treatment for this disease for many clinicians. With light therapy, the process is reversed by reducing the time of melatonin release.
In phototherapy, special light sources in the range of 1500 to 10000 lux that mimic daylight are used and no activity is performed for at least 30-40 minutes, preferably 2-4 hours, every day. , preferably reading books, is done in front of this light. Since ultraviolet rays are harmful to the eyes and skin, the lights used in phototherapy contain minimal UV rays. Solarium should not be used for this purpose. It is recommended to look directly at the light source for 1-2 seconds every hour, but this period should not be longer. It is generally recommended to continue light therapy until there is sufficient sunlight outside. It is recommended that phototherapy be performed in the morning rather than at night. Phototherapy applied at night may slow down melatonin secretion and cause sleep problems. Like all other treatments, light therapy should be done under the supervision of a doctor. This is especially important for those with another type of depression, those with light-sensitive skin, or those with an eye condition that can be damaged by light.
Patients who respond best to phototherapy are MDD patients without personality disorders and with atypical vegetative symptoms. It is said. Phototherapy is used not only in MDD, but also in chronobiological sleep disorders, rhythm disorders that occur during long plane trips (jet lag), shift work or similar situations.
In addition to phototherapy, cognition therapy is also used.
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