Is Seasonal Depression Real? All You Need To Know About SAD

Seasonal depression or seasonal affective disorder (SAD) is real. It causes people to experience mood changes during a particular season. If you experience SAD, a greater understanding of the condition may help you to alleviate your symptoms and have a better quality of life.

Have you considered clinical trials for Seasonal affective disorder (SAD)?

We make it easy for you to participate in a clinical trial for Seasonal affective disorder (SAD), and get access to the latest treatments not yet widely available - and be a part of finding a cure.

What is seasonal affective disorder?

Seasonal affective disorder (SAD) is a subtype of major depression. Unlike major depression, which is always present, SAD lasts for a few months at a time and is linked to seasonal change. 

SAD is often referred to as winter depression because it affects most people during late fall or winter. However, SAD isn’t limited to the colder months, and although less common, some people experience SAD during late spring and summer

Someone who has SAD only experiences depression during a particular time of the year. 

Once that time of year has passed, the depression goes into remission until the same time the following year. 

What causes seasonal affective disorder?

A single cause of SAD has not been identified. Instead, SAD is likely caused by environmental and biological factors.

Environmental factors include:

  • Seasonal changes

  • Light

  • Location

Biological factors relate more to the internal body clock or circadian rhythm, which regulates your body’s daily cycles.

SAD is most common in parts of the world that experience four seasons. It is experienced in northern areas of the United States and Canada or places closer to the north or south poles (locations with high latitudes). In contrast, people who live in tropical areas close to the equator are least affected by SAD.

Places with high latitudes have long summer days and short winter days. The seasons are also extreme in these places, with some countries experiencing hot summers and freezing winters.

Due to the huge variation between summer and winter, the body has to adjust to different light exposure levels and new temperatures as the seasons change. Some people find it more challenging to adapt to these changes because it disrupts their body clock.

The body clock, or biological clock, regulates the body’s 24-hour sleep-wake cycle and other daily cycles. These cycles are also known as the circadian rhythm.

Light is one factor that regulates the body clock. Therefore, when seasonal changes and weather alter the light in your environment, this can disrupt your body’s cycles.

Your body clock relies on light as a stimulus for sleeping and waking. At night, when it’s dark, your brain releases a hormone called melatonin, and during daylight hours, melatonin is suppressed. 

Researchers have linked melatonin to SAD because people with SAD have elevated melatonin levels. This occurs when the brain releases melatonin during the day in winter due to the decreased amount of daylight. 

Scientists have also discovered that people with SAD have reduced levels of serotonin. Like melatonin, serotonin helps to regulate the body clock. 

Low levels of serotonin can also lead to depression. The body might have difficulty producing serotonin due to a lack of light since it requires vitamin D to make it. Your body naturally derives vitamin D from sunlight. 

Overall, the underlying cause of SAD is complex, and some genetic factors also play a role. 

People with summer SAD are affected by too much light, which may also affect melatonin production since light suppresses the release of melatonin. However, research on SAD tends to focus on winter SAD since summer SAD is uncommon. 

Winter seasonal affective disorder 

SAD predominantly occurs during winter and affects fewer people during summer. The symptoms associated with winter SAD are slightly different from those of summer SAD. 

Symptoms of winter SAD include:

  • Depression

  • Feelings of hopelessness

  • Social withdrawal

  • Tiredness

  • Increased appetite

  • Cravings for carbohydrates or sweet food

  • Weight gain

  • Delayed onset of sleep

  • Excessive daytime sleepiness and prolonged sleep at night

The symptoms of winter SAD can start during late fall and may persist throughout winter. You may notice that your SAD symptoms occur when the days begin to feel shorter or when the clocks go back from daylight savings. 

A lack of daylight triggers winter SAD since the days are shorter during winter. Your body clock becomes disrupted, impacting your sleep, eating habits, and mood. 

For instance, some people might feel more tired during winter due to the increased darkness. Waking up on cold, dark mornings is difficult, and people with winter SAD tend to oversleep. 

Additionally, colder weather may prevent some people from going outside to exercise. A lack of exercise can also contribute to SAD because regular exercise is good for general well-being.

The main symptoms of winter SAD are a low mood and the feeling of hopelessness. As a result, people with winter SAD can feel very depressed, preventing them from socializing. 

These symptoms disappear as the days become longer, typically around spring or early summer. During the summer, the symptoms are absent and will not return until the following winter. 

Summer seasonal affective disorder

Summer SAD occurs less frequently than winter SAD. 

The symptoms of summer SAD are: 

  • Depression

  • Agitation

  • Restlessness

  • Anxiety

  • Irritability

  • Tiredness

  • Decreased appetite

  • Insomnia – difficulty falling asleep and staying asleep

  • Episodes of violent behavior 

The symptoms of summer SAD may start during late spring and last throughout summer. Your symptoms occur as the days feel longer or when the clocks jump forward with daylight savings. 

Unlike winter SAD, summer SAD is triggered by too much daylight. Too much light can disrupt the body clock, impacting your mood, sleep, and appetite. 

People with summer SAD find it challenging to go to sleep when they typically would. They might also wake up earlier than usual. 

These symptoms disappear as the nights become longer during late summer or fall. Although you feel relief in the winter months, your symptoms will come back the following summer. 

Who does seasonal affective disorder affect?

SAD has the potential to affect anyone. However, some people might be more susceptible than others.

As mentioned previously, location has a significant influence on SAD. People who live closer to the North Pole or the South Pole are most susceptible. In contrast, people who live closer to the equator are affected less.

Other people more prone to SAD include:

  • Women: Females are more likely to develop SAD than males

  • People with a history of mild depression

  • People with sedentary lifestyles: Those who do little or no exercise are more at risk

  • Young adults: Younger people are more likely to experience SAD, but older people are also affected

How is seasonal affective disorder diagnosed?

If you suspect that you have SAD and you’re yet to be diagnosed, it may help to record when you experience symptoms. Doing so will help you determine whether a seasonal pattern is linked to your depression.

A doctor might use a scale, such as the one set by the DSM-IV,¹ as a guide to diagnosing your SAD. 

For example, the DSM-IV sets these criteria for diagnosing SAD:

  • There must be a consistent relationship between depressive episodes and a particular season.

  • Complete remission from depression must occur outside of a particular season every year.

  • Over the last two years, there must be a history of SAD to show a true relationship between a seasonal change and depression.

  • If depressive episodes are experienced outside of a particular season, then non-seasonal episodes must occur less frequently than seasonal ones.

The important thing to remember is that criteria such as these are used as a guide only. Your doctor might assess other aspects of your situation, such as your symptoms, to provide a diagnosis.

Are there treatment options? 

Although simple lifestyle changes tend to have better effects than treatment alone, you can receive some treatments, and light therapy is often the first-line treatment. 

Many people try light therapy, which involves increasing the amount of light in your home or workplace during winter. Lightboxes have also been suggested to increase the amount of light.

Some people take antidepressants during their affected season and may start this treatment before symptoms begin.

Vitamin D supplements may also be suggested for people with SAD during winter as these supplements might help the body synthesize serotonin when there’s less sunlight.

Exercise and healthy eating are also advisable during the winter months as your body is more prone to becoming rundown during the winter months.

When to see a doctor

If you suspect that your depression is linked to a particular season, seeing a doctor before that time of year might help you prevent SAD or stay on top of it.

If SAD is troubling you or your symptoms worsen, you should not hesitate to see a doctor.

The lowdown

SAD is a real disorder, and with awareness increasing of this condition, more people are starting to address their seasonal depression. You can try a range of treatments for SAD, and simple lifestyle changes can also help.

Have you considered clinical trials for Seasonal affective disorder (SAD)?

We make it easy for you to participate in a clinical trial for Seasonal affective disorder (SAD), and get access to the latest treatments not yet widely available - and be a part of finding a cure.

Joining community groups and exercise programs for my condition made me feel empowered – but I want to be part of finding a cure.
Peter, 64

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