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22 Jun 2020, by moni

What is seasonal affective disorder (SAD)?

I just cannot get away from my fascinating and mind-opening psychology books. I am sure you have already heard about seasonal affective disorder (SAD), when it comes to fall and some of us become depressive and rather spend their time at home in bed, then going out socialising.

Let’s start with explaining what SAD is exactly, the symptoms and then the fascination biological causes of this ‘grumpy’ mood disorder.

Often called “winter depression” , SAD is a mood disorder which is caused by changes in the amount of light we receive. It is characterised by a depressive mood and typically starts in autumn when the days get shorter.

Symptoms can vary in severity and, in some cases, SAD can have a serious impact on everyday activities. They can appear and disappear with seasonal changes, they usually start at the same time of the year in autumn, and include low mood, a loss of interest in everyday activities, irritability, desperation, feelings of guilt and worthlessness. Other common symptoms include feelings of lassitude, all day long drowsiness, difficulties in waking up despite longer sleeping hours. SAD can affect one in three people.

Diagnosis of SAD is difficult due to its seasonal nature. Mood, lifestyle, diet, season specific/seasonal behaviours, changes in thinking and family history are all considered in the assessment of SAD.

Treatment involves psychotherapy (e.g. CBT and counselling) and/or changes in lifestyle (e.g. ensure the access to as much sunlight as possible, using natural light simulating light bulbs, daily outdoor activities).

But what are the causes of SAD? It is known that the amount of sunlight has an impact on the mechanism of the hypothalamus. That is, the amount of sunlight manipulates the production of melatonin and serotonin. Melatonin is a hormone which regulates the sleeping cycles, while serotonin is a neurotransmitter responsible for mood regulation. Melatonin production occurs in the pineal gland and is turned on by the darkness and inhibited by the sunlight.

In winter, the days become shorter, there is less sunlight and therefore there is an increase in the production of melatonin, which in turn results in the feelings of sleepiness, fatigue and a need for more sleep. Meanwhile, serotonin levels decrease causing a low mood. In addition, the desire to stay in bed and sleep longer narrows down social life. Increased appetite for carbohydrates puts the individual with SAD at risk of gaining weight. Persistent lassitude affects both family and work life.

As opposed to winter, in summer, melatonin production falls, while vigilance/alertness rises. Serotonin production increases resulting in an optimistic mood. The amount of sleep is sufficient, not too much and the individual is energetic. Having more energy allows the person to be more active and engage in social activities. Hunger for carbohydrates decreases.


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