Seasonal Depression

While many of us enjoy the variety of the four seasons, there are countless others who not only dread winter, but are physically and mentally effected by the colder months. To the point where the change in seasons can weigh so heavily on their mental health, they develop depression.

Seasonal affective disorder (SAD) is a condition where its sufferers can fall into a heavy state of depression as soon as the thermometer drops. While it can be easy to joke about having the winter blues, seasonal affective disorder has made its way into medical manuals across the globe as a legitimate mental health condition. Seasonal affective disorder was first described in 1984.

Around 6% of Americans, especially in Northern Regions suffer from SAD. However, moving to UK, the stats are a lot higher with as many as 1 in 3 people experiencing SAD and 57% of residents stating that their overall mood is a lot worse in winter months.


Notably, around 10 to 20% of recurrent depression cases follow a seasonal pattern, with the predominant pattern being fall and winter depression. Seasonal affective disorder comes with a set of very predictable symptoms, that often return each year when fall or winter sets in.

These symptoms can affect your day to day life as it makes it hard to go about your daily tasks without struggle. As soon as spring or summer comes around, the depressive symptoms usually dissipate. The predictable symptoms that might arise in the colder months include:

  • High consumption of comfort foods, particularly those high in carbohydrates, fats and sugars and subsequent weight gain
  • Low energy, lethargy and fatigue
  • Loss of libido
  • Lack of motivation or inspiration
  • Excessive time spent indoors or in bed/excessive time sleeping
  • Lack of self-care
  • Isolation from social activities
  • Feelings of worthlessness and general despair
  • Suicidal thoughts
  • Persistent crying for no explained reason
  • Loss of interest in activities that you are usually very driven to participate in
  • Reduced immune system and constantly getting sick
  • Reliance on stimulants such as caffeine, drugs or alcohol
  • Forgetfulness
  • Feeling of being alone even though you might have a great network of friends and family
  • Anxiety
  • Feeling frequently angry or irritable with no plausible link

Causes and diagnosis of seasonal depression

There’s no doubt about it, shorter, colder days with less sunshine certainly have an effect on our overall happiness. Just imagine the regions of the world such as Norway, where the sun doesn’t rise above the horizon for an entire 51 days! That’s 51 days living in darkness!

Seasonal affective disorder (SAD) or seasonal depression is a type of depression that lasts throughout autumn or winter months and is believed to be caused by the lack of sunlight, shorter days and lack of warm temperatures. There are multiple hypotheses as to the true causation behind SAD and it seems there is no one true link, rather a combination of factors including:

A disruption in your circadian rhythm 

Experts believe that one causation of SAD is linked to a disruption in our natural circadian rhythm, otherwise known as your body clock, which controls your sleep/wake cycle. Your cycle is directly influenced by light or darkness. 

If you were to wake around the same time each morning year round, your circadian rhythm will naturally shift with the seasons, but your wake time remains unchanged. Therefore, your sleep/wake cycle can end up misaligning. SAD can be caused by a mismatch in the sleep/wake cycle and the natural circadian rhythm, which is why light therapy and administration of melatonin are used in the treatment of SAD, to attempt to reset the body clock.

Altered levels of melatonin 

This misalignment can disrupt the release of melatonin, the sleep hormone, as it is usually slowed down during daylight hours, in order to keep you awake and alert. As the evening goes on, the production of melatonin is increased. In fact, your circadian rhythm controls many aspects of your body functions including blood pressure, mood, metabolism and body temperature.

For night shift workers, their health can suffer dramatically from their natural body clock being thrown out by alterations in sleep patterns. You could picture someone who suffers from SAD as being similar, the shorter duration of daylight alters their natural body clock, with melatonin being produced at a greater rate, therefore causing lethargy and associated negative emotions.

If you suffer from SAD, it is said that you have trouble with the overproduction of melatonin.

Altered levels of serotonin 

Less exposure to sunlight has been associated with lowered levels of serotonin. In general, we all have lower serotonin levels in winter. In fact, serotonin has been used in antidepressant medication since their discovery in the 1950s.

Serotonin even has a role to play in helping to convert to melatonin during the darkened hours. It has been recognized that those who suffer from SAD have lower levels of serotonin during the day and have trouble in producing melatonin when needed at night.

The role of serotonin is that it helps to regulate mood, sex drive, memory, emotional behavior, appetite, and the regulation of the circadian rhythms. Serotonin is a happy hormone and when we have an abundance of it we feel content with our lives.

Genetics may play a role 

In studies of the patterns of SAD in family members, it was noted that there was an increased prevalence in the first-degree relatives of SAD patients. Particularly, one study of twins estimated that genetic factors of SAD account for 29% of overall variance.

Diagnosis of seasonal depression 

There is no one set test in diagnosing seasonal affective disorder (SAD). Rather particular criteria must be met in determining a diagnosis of SAD. The clearest diagnosis is feelings of depression and the symptoms of SAD present at the same time each year, where the temperate begins to plummet and winter kicks in. Your doctor may ask the following questions:

  • Do you find that your depression worsens throughout the cooler months, but almost entirely vanishes in spring or autumn months? 
  • Have you noticed a clear pattern of the timing of these symptoms for at least two years in a row?
  • How would you rate your overall lifestyle patterns including exercise, diet, sleeping patterns and self-care? Do these patterns change throughout winter?
  • Is it hard for you to go about your everyday activities in the cooler months? Do you find that your symptoms prevent you from carrying out your necessary daily tasks?
  • Are you drinking more alcohol or relying on drugs in the colder months?

Your doctor may also carry out basic tests such as blood tests in order to rule out any other condition with similar symptoms.

Treatment options for seasonal depression

There are multiple approaches to seasonal depression, besides just moving to somewhere warm year round, though if that is an option, it may be a good one.

Light therapy 

Light therapy is currently the most widely used treatment for seasonal affective disorder (SAD). Light therapy has proven to be an effective treatment for those suffering from SAD, given that winter is comprised of shorter days, less actual daylight, and less exposure to sunlight.

Light therapy uses an artificial lamp that mimics sunlight by way of full-spectrum light. Serotonin turnover is at its lowest in the winter season, but its production can be increased with luminosity.

The recommended exposure is to sit in front of a light machine each morning for 20 to 60 minutes, although studies show that 40 minutes is the optimal time to receive most benefits. Those suffering from SAD are able to purchase at-home light kits and use them daily through the colder months.

It can only be an effective treatment if used properly. Light therapy requires a set amount of time each day to be spent in front of the light machine and missing even one session can see less-effective results.

Light therapy is not a new thing, in fact over the last 20 years multiple studies have consistently shown that it is an effective treatment for those suffering from SAD, and is also showing benefit to those that suffer from depression in general.

There’s certainly been a lot of skepticism about the use of light therapy machines, largely due to many marketing companies jumping on top of the hype. What’s important is that there is a large body of scientific evidence, showing its effectiveness in lifting overall mood and a convenient method to see past SAD during the colder months.

One such skepticism that remains is the use of a light visor, which you can picture as a poorly fashioned sun visor from the ‘90s. It is a head mounted unit that emits light frequencies, which is considered to be highly portable, lightweight and convenient. However, a few questions remain as to its efficiency, with one study noting no difference between 105 patients with SAD being treated with the light visor, as compared to patients receiving no treatment at all.

When comparing light therapy boxes to the use of antidepressant medication over a five-week period 40 SAD patients responded more positively to light therapy than medication. Light therapy also improved depression scores faster. You don’t have the same detrimental side-effects with light therapy as you do with antidepressant medication, such as addiction, withdrawal, insomnia or drowsiness.

It’s interesting to note that light therapy can also be used as a preventative measure before signs of SAD even develop. Even if you commence light therapy at the earliest symptoms, studies show that it can alleviate, or perhaps prevent depression from occurring all together.

Of course individual circumstances do vary greatly, but if you have previously been diagnosed with SAD then light therapy is highly recommended for preventing mood disturbance, lethargy and fatigue in the winter months. Response rates to light therapy are around 80% in select patients.

Vitamin D supplementation

Vitamin D deficiency is now a global health concern. With depression increasing by 8-14%, and suicide as much as 50%, without sufficient intake of this important vitamin. There have been many studies carried out as to the effectiveness of using vitamin D to treat depression, but not without much controversy. In one in-depth report published on National Institutes of Health, it was noted that vitamin D demonstrated similar effect to that of antidepressant medication

Funnily enough, you won’t often hear of the level of effectiveness of vitamin D in treating depression, especially considering the global depression drug market is set to boom to 16.80 billion USD by 2020. The use of supplements like vitamin D is cost-effective, simple, convenient and doesn’t come with the burden of side-effects that are directly linked to antidepressants. Further, supplements can also be used in the prevention of developing SAD in the first place.

Given winter carries shorter days and in many regions less exposure to sun, and of course colder temperatures, we generally spend a lot more time indoors. Ultraviolet rays from the sun are important to help the body produce vitamin D naturally, as our bodies cannot produce vitamin D alone. We have also learnt a great deal about the importance of exposure to sunlight, in order to prevent chronic diseases.

However, because we have been warned by authorities about the dangers of skin cancer and melanoma, we have been placed in a position where we feel we need to avoid the sun entirely. Ironically, excessive UVR exposure accounts for only 0.1% of the total global burden of disease, as compared to figures showing that 50% of the global population are now deficient in vitamin D.

So whether you supplement on vitamin D or you’re able to exposure your skin directly to UV rays from the sun during winter, both options will provide beneficial effect in reducing depressive symptoms associated with SAD.


While it can take several weeks to experience the benefits of antidepressants, they are commonly prescribed for those that do not feel positive benefit of light therapy, or have more severe symptoms of SAD.

Selective serotonin reuptake inhibitors (SSRI) are the leading types of antidepressants prescribed for those suffering from SAD. This medication helps to increase the availability of serotonin in your body. When there are higher levels of serotonin available, depressive feelings subside.

If you believe that you’re suffering from SAD in the cooler months, by consulting a doctor or psychiatrist sooner rather than later, you can get on top of your depression and prevent its worsening. By understanding the patterns of seasonal affective disorder, it will help you to tackle the symptoms, preventing you from feeling so isolated throughout the winter months.

Exercise programs

Of course there are numerous barriers to those suffering from SAD in actively participating in any exercise program, given that they already lack motivation, inspiration, and are suffering from fatigue and other limiting emotions. This is just one of the reasons why it has been quite hard to measure the successfulness of any exercise treatment program for depression.

What is known however, is that exercise releases feel-good hormones such as dopamine, therefore helping to light up the pleasure center of the brain. Particular dopamine receptors have been shown to enhance long-term depression.

Other than the more obvious physical benefits of exercise, regular engagement in movement helps to enhance coping mechanisms for external or internal life challenges, therefore offering protective mechanisms against stress. The power of exercise also extends to treating psychiatric illnesses, supporting recovery from brain injury and improving neurological function.

Exercise helps to increase antioxidant defenses, which in turn boosts immunity and helps to clear toxins from the body. Those that suffer from major depression or anxiety have been recognized as having lowered total antioxidant levels.

Finding methods to naturally increase antioxidant capacity, without the need for antidepressants surely must be a much more effective approach to mental health in the long term. Of interest, antidepressant medication has been shown to increase antioxidant levels, while simultaneously decreasing oxidative damage.

Serotonin is a neurotransmitter that is largely behind your emotional processing. In both animal and human studies, it has been shown that when we engage in regular exercise, the availability of serotonin is increased. Serotonin helps to regulate so many functions such as mood, appetite and sleep patterns. However, the way in which serotonin is released into the body is actually a lot more complex than first imagined by scientists in studying the human body.

Changes in diet

By increasing one essential amino acid in your diet you can boost serotonin levels.

Serotonin is actually synthesized by an essential amino acid called tryptophan. When this important amino acid is depleted, it results in lowered levels of serotonin, which has been shown to lower mood, increase irritability and aggression. Tryptophan has a direct effect on sleep and helps to improve morning alertness and attention.

Foods that have been found to contain high levels of tryptophan include:

  • Eggs
  • Salmon
  • Seeds and nuts
  • Cheese
  • Chicken
  • Brown rice
  • Beans and legumes

Where possible spend time in the sun

Unless you do in fact live in Norway or other regions that stay in complete darkness through the winter months, you should be able to take advantage of small windows of opportunities to be in the sun. You can also ensure that your home environment is as light and bright as possible, by opening blinds and curtains to allow natural light in.

Studies are showing that the skin is able to produce serotonin through direct exposure to sunshine. In evaluating a combined treatment of vitamin D and exercise, it’s interesting to note that a deficiency in vitamin D has been recognized as a key factor to dysfunctional serotonin activation.

So whether you supplement on vitamin D, or are able to spend time in the sun each day, it’s important to find ways to boost your natural supplies. Foods that are high in vitamin D include:

  • Wild caught fish such as salmon or mackerel
  • Milk
  • Oatmeal
  • Canned tuna
  • Mushrooms

related articles

From our Writers' Desk


© Copyright 2024. All rights reserved.