Seasonal Affective Disorder (SAD): Causes, symptoms, treatment and prevalence

Overview of Seasonal Affective Disorder (SAD) 

SAD, which is the acronym for Seasonal Affective Disorder, refers to a form of depression caused by the change of seasons. It generally appears in the late fall or early winter which is found to be continued throughout the months of winter. However, though it can also be initiated in the months of summer and spring, this is quite uncommon. The mild version of Seasonal affective disorder is often referred to as winter blues, but its intensity is not as high as SAD.

Daily life is adversely affected by this disorder, which also influences how an individual feels and thinks. Nevertheless, there are treatments which can help individuals to overcome this type of challenging situation. Seasonal depression is the term which is also interchangeably used for seasonal affective disorder.

Prevalence of SAD

Identifying the prevalence of seasonal depression is quite difficult as many cases of this disorder are not reported and, therefore, underdiagnosed. However, it is found that women usually suffer from seasonal affective disorder four times more than men. This generally occurs among people between the age group of 18 to 30 years. People who live far away from the equator in the northern latitudes are more likely to experience this disorder.

For instance, 1 per cent of people living in Florida and 9 per cent of those who live in Alaska are found to be experiencing SAD in the United States. In Canada, the prevalence of winter blues and SAD among the population are respectively 15 per cent and 2 to 6 per cent. In the case of the United Kingdom, around 20 per cent are sufferers of winter blues, while 2 per cent are of seasonal affective disorder. There are around over 10 million people in India who suffer from SAD.

In terms of analyzing the risk factors, having bipolar disorder can be accountable for worsening the symptoms of SAD among individuals. Additionally, individuals are most likely to experience seasonal depression who have blood relatives suffering from any kind of depression.

Symptoms

The symptoms of seasonal depression vary according to the time of its occurrence. The most common symptoms linked with the seasonal disorder appearing in late fall or early winter include concentration problems, depression and anxiety, lack of energy and tiredness, sleeping problems or oversleeping, lack of interest in social activities and many others. On the other side, the symptoms of summer SAD, which is rare, include anxiety, weight loss, insomnia, violent behavior and agitation. 

Causes of seasonal affective disorder

The exact causes of the occurrence of seasonal depression are still unknown among the researchers. However, the deficiency of sunlight exposure increases the chances of this disorder occurring among people. The following are some of the factors which can be considered as accountable regarding this aspect.

Shifting in the biological clock 

Major biological shifts are observed in the biological clock of the people when there is less sunlight in fall and winter. This internal clock is accountable for regulating the sleep, mood and hormones of the human body. During the time of this shift, the individuals step out from the daily schedule with which they were familiar, and as a consequence, they are unable to make adjustments to the shiftings in the daylight length, leading to the occurrence of the feeling of depression.

Imbalance in brain chemical

Neurotransmitters, the chemical messengers, are responsible for sending communications between nerve cells or neurons. There is serotonin in these chemicals, which leads to feelings of happiness. A reduction in sunlight leads to a considerable drop in serotonin, which can decrease happiness feelings and trigger depression.

Deficiency of Vitamin D

The level of serotonin is also linked with vitamin D. Since sunlight is considered one of the major sources of vitamin D, therefore, in the season of winter, a deficiency of vitamin D can be observed in the human body due to the lower intensity of sunlight at that time. This can reduce the level of serotonin and, therefore, can adversely impact the mood of the individuals.

Increased melatonin

The sleep-wake cycle of human beings is considerably controlled by melatonin which is a hormone produced by the pineal gland in the brain. Less sunlight can cause the production of melatonin in large volumes in some people. For this reason, many people feel sleepy and inactive during the time of winter.

Negative perceptions 

People suffering from seasonal depression are often found to have anxiety, stress and negative perceptions about the winter. There is confusion among researchers about whether these negative thoughts are the outcomes or causes of seasonal depression.

Treatment methods

The treatment methods for seasonal depression generally involve a combination of antidepressant medication, Vitamin D, light therapy, and counselling. In some cases, dietary supplements and herbal remedies are chosen to get relief from depression symptoms, but there is no clear evidence regarding the effectiveness of these treatments.  A discussion has been made below on the effective treatment options.

Light therapy

Light therapy, which is also termed phototherapy, refers to a type of treatment for depressive disorder which involves exposure to a source of artificial light. During the session of light therapy, the person suffering from seasonal depression is required to sit close to a lamp or light box accountable for emitting a bright light. These have the potential of imitating the natural sunlight. The standard output varies from 2500 to 10000 lux of the light therapy box.

The unit by which light brightness is measured is lux. For the treatment, the individuals are given exposure to 10000 lux of artificial light daily in the morning for 20 to 60 minutes based on the requirements. Light therapy helps to balance the required level of serotonin in the human body, which contributes to positive mood regulation as well as balanced sleep patterns, leading to the reduction of depression.

Antidepressant medication

Like any other depression, SAD is also observed to be connected with the inefficiency in brain serotonin activity. Hence, second-generation antidepressants (SGAs) are often recommended as promising solutions for SAD. In this regard, fluoxetine and Bupropion are considered quite effective medications for the treatment of seasonal depression.

Vitamin D 

Lifestyle problems, less exposure to sunshine, and insufficient dietary intake are the vital causes of low levels of vitamin D, which often triggers seasonal depression. Therefore, healthcare professionals often suggest the intake of vitamin D supplements along with the involvement of a healthy lifestyle to improve the situation of depression. It is also recommended to the sufferer to spend time outdoors.

Counselling

Individuals with seasonal depression can get support to exit from the depressed situation through counselling approaches. According to a study, offering Cognitive Behavioural Therapy (CBT) for two 90-minute sessions per week for six weeks has the same effectiveness as light therapy. Moreover, walking, yoga, exercise, meditation and intake of a healthy diet are also beneficial for addressing the symptoms of depression. It is also suggested that the individuals spend more time with their family members, relatives and others with whom they feel enjoy, as this can offer them support to reduce their depression.

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