Seasonal Affective Disorder
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Seasonal Affective Disorder

Seasonal affective disorder occurs in climates where there is less sunlight at certain times of the year. Symptoms include fatigue, depression, hopelessness and social withdrawal

Post by on Friday, February 12, 2021

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Recently, the Diagnostic and Statistical Manual of Mental Disorders, 5th edition, has changed the name “seasonal affective disorder,” or SAD, to “depressive disorder with seasonal pattern.” The new name is not as catchy as “SAD,” or “SAD” but it does describe the condition more precisely. That’s because depressive disorder with a seasonal pattern is not really a distinct disease, but rather depression that worsens at the same time each year, usually in the late fall and winter. So let’s first review depression. Depression, or major depression, is a serious condition where someone’s life isn’t enjoyable and it interferes with someone’s day-to-day life, like working, studying, eating, and sleeping. The causes of depression are not fully known, but it is thought to involve a deficiency of monoamine neurotransmitters in the brain, like dopamine, norepinephrine, and especially serotonin. In depressive disorder with seasonal pattern, there’s a strong relationship with the circadian rhythm, which is an internal clock that keeps your body in tune with the rising and setting of the sun.


At the base of the brain, is a region called the hypothalamus, and within it are a group of neurons located in a specific spot called the suprachiasmatic nucleus or SCN. The neurons or the nerve connections get information about light from optic nerves, and use that information to run the circadian rhythm. The suprachiasmatic nucleus relays that information to the pineal gland, a tiny cone-shaped structure near the hypothalamus. And when it’s dark outside, the pineal gland releases the hormone melatonin, which is chemically related to serotonin.

Melatonin lowers your heart rate and body temperature, which helps you go to sleep. When it’s light outside, the pineal gland stops releasing melatonin, and that has the opposite effect - raising your heart rate and body temperature, and that keeps you awake. A risk factor for developing depressive disorder with seasonal pattern is having a sleep phase delay, which is when a person makes too little melatonin at night. This can be due to things like decreased sensitivity to changes in light, problems with the communication between the retina and the hypothalamus, and even external sources of light like late-night computer use.

A sleep phase delay can result in a person’s internal clock having more than the standard 24 to 25 hours in a day, which might sound awesome - but actually it means that a person may not be able to sleep until at least eighteen hours after they woke up that day. Day after day, that quickly becomes exhausting. It can be hard for anyone to adjust to the late sunrises and early sunsets of winter, especially those who live in higher latitudes.  But for those with a disordered circadian rhythm, the shorter days seems to somehow interfere with monoamine production, causing the person to become depressed.


Another mechanism that may be involved relates to vitamin D, which is largely obtained in a reaction that relies on sunlight. Vitamin D is involved in the synthesis of serotonin and dopamine in the brain, and if someone is already deficient in vitamin D decreased sunlight, and therefore decreased synthesis of monoamines, might push a vitamin-D deficient person into depression. Both the sleep phase delay and vitamin-D deficiency ideas hold promise, but they don’t yet explain those few people who get depressive disorder with seasonal pattern in the summer.

Symptoms of depressive disorder with seasonal pattern are similar to those of depression, and include intense feelings of worthlessness or guilt, and a lack of enjoyment in activities they took pleasure in during other times in the year. They may find it hard to concentrate, and in severe cases, have thoughts of death or suicide. So, when it comes to diagnosis, for the depression to be truly seasonal, it must occur in the same season each year for at least two years in a row, and the symptoms must diminish or disappear with the new season. It’s also important not to confuse seasonally-triggered depression with depression caused by recurring psychological or social stressors, like having job pressures or living alone during certain months of the year. Treatment of depressive disorder with seasonal pattern usually includes light therapy, medication, and psychotherapy. In light therapy, a person sits close to an intensely bright light box for 30 to 90 minutes every morning.


Unlike the light bulbs you’d normally use around your house, light-therapy boxes have light wavelengths that allow the skin to produce vitamin D. Antidepressants can also be helpful - for example, selective serotonin re-uptake inhibitors can increase serotonin levels, and bupropion can increase norepinephrine and dopamine levels. Finally, cognitive behavioural therapy can be particularly useful in helping people identify and manage their feelings. Hypnotherapy can be used to aid relaxation and persistent issues that may act as triggers.

Alright, as a quick recap, seasonal affective disorder is a mood disorder characterised by depression that occurs at the same time every year. Seasonal affective disorder occurs in climates where there is less sunlight at certain times of the year. Symptoms include fatigue, depression, hopelessness and social withdrawal. Treatment includes light therapy (phototherapy), talk therapy like Cognitive Behavioural Therapy and Hypnotherapy and medication.


Recommended Viewing

Seasons’s Greetings (2019), a short film that revolves around a man in Mumbai suffering from SAD (Seasonal Affective Disorder). Tired with the summer months he impatiently waits for the monsoon to hit the city. When the monsoon finally arrives, he experiences a low mood and often gets frustrated by the rains and prays for it to go away.


(Decency Rajput Chowdhury is a Consultant Clinical Psychologist and Clinical Hypnotherapist at VIMHANS, New Delhi and can be reached on



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