Seasonal Affective Disorder
What is SAD?
Seasonal affective disorder (SAD) is a type of depression that comes and goes in a seasonal pattern. SAD is sometimes known as “winter depression” because the symptoms are more apparent and tend to be more severe during the winter.
The symptoms often begin in the autumn as the days start getting shorter. They’re typically most severe during December, January and February. SAD often improves and disappears in the spring and summer, although it may return each autumn and winter in a repetitive pattern.
Symptoms of SAD can include:
- Persistent low mood
- Loss of pleasure or interest in normal everyday activities
- Feelings of despair, guilt and worthlessness
- Lethargy (lacking in energy) and sleepy during the day
- Sleeping for longer than normal and finding it hard to get up in the morning
- Craving carbohydrates and gaining weight
For some people, these symptoms can be severe and have a significant impact on their day-to-day activities.
What Causes SAD?
The exact cause of SAD isn’t fully understood, but it’s often linked to reduced exposure to sunlight during the shorter autumn and winter days.
The main theory is that a lack of sunlight might stop a part of the brain called the hypothalamus working properly, which may affect:
- Production of melatonin – melatonin is a hormone that makes you feel sleepy; in people with SAD, the body may produce it in higher than normal levels.
- Production of serotonin – serotonin is a hormone that affects your mood, appetite and sleep; a lack of sunlight may lead to lower serotonin levels, which is linked to feelings of depression.
- Body’s internal clock (circadian rhythm) –your body uses sunlight to time various important functions, such as when you wake up, food digestion, appetite, energy levels, sleep quality and length and mood. Lower light levels during the winter may disrupt your body clock and lead to symptoms of SAD.
It’s also possible that some people are more vulnerable to SAD as a result of their genes, as some cases appear to run in families.
Various things have changed over time which means that we no longer gain access to enough natural daylight. Also changes in lifestyle have diminished the body’s natural ability to regulate the body clock.
- Two hundred years ago 75% of the population worked outdoors now less than 10% of the population work in natural outdoor light.
- A modern day no longer starts at the break of dawn and ends at sunset.
- Workdays are getting longer and many people face shift work schedules.
- The advent of electric lighting allows social gatherings and personal activities to extend well into the night.
- In the UK and Ireland we are more susceptible to SAD as we are situated in the higher latitudes of the northern hemisphere. As a result, we experience large changes in light levels between the summer and Winter. There is also darker gloomier weather.
Treatment for SAD
- Lifestyle measures, including getting as much natural sunlight as possible, exercising regularly and managing your stress levels
- Light therapy – where a special lamp called a light box is used to simulate exposure to sunlight
- Talking therapies, such as cognitive behavioural therapy (CBT) or counselling
- Antidepressant medication, such as selective serotonin reuptake inhibitors (SSRIs)
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