We have all felt it at some point. Those woeful wintertime blues strike out of nowhere, sapping your joy and making you long for blue skies and sunny days. But what about when this brief, season-related sadness isn’t brief at all and keeps you from accomplishing basic tasks? This is seasonal affective disorder (SAD).
What exactly is SAD, and what can you do about it? Is medication your only option? Not quite. Read on to learn more about this seasonal depressive disorder and how light therapy could be the key to regaining your life and happiness in the wintertime.
What is SAD?
SAD, also called seasonal or winter depression, is a form of depression brought about by seasonal changes and lack of sunlight. Most people with SAD experience depressive symptoms around 40 percent of the year.
Winter pattern SAD, where the symptoms start as the days get shorter and the weather gets colder, is the most common. However, rare cases of summer SAD have been reported. Remember, SAD will alleviate during a specific part of the year. Anyone with persistent depressive symptoms likely has another form of depression.
According to the National Institute of Mental Health, symptoms of sad include:
- Feeling depressed most of the day, nearly every day
- Losing interest in activities you once enjoyed
- Experiencing changes in appetite or weight
- Having problems with sleep
- Feeling sluggish or agitated
- Having low energy
- Feeling hopeless or worthless
- Having difficulty concentrating
- Having frequent thoughts of death or suicide
For winter-pattern SAD, additional specific symptoms may include:
- Oversleeping (hypersomnia)
- Overeating, particularly with a craving for carbohydrates
- Weight gain
- Social withdrawal (feeling like “hibernating”)
Specific symptoms for summer-pattern SAD may include:
- Trouble sleeping (insomnia)
- Poor appetite, leading to weight loss
- Restlessness and agitation
- Anxiety
- Episodes of violent behavior
Note: For this article, we will be referring to the more common winter-onset SAD.
What causes seasonal affective disorder?

The life-giving power of sunlight cannot be overstated. This burning star balances our sleep, regulates our mood, and informs our biological clock. Though scientists have yet to agree on the exact mechanism behind SAD, lack of sunlight plays a key role in each of the following commonly accepted theories.
Lack of serotonin
Serotonin is a neurotransmitter that acts as a mood stabilizer and can help regulate sleep and boost feelings of well-being. Sunlight can directly stimulate the production of serotonin when it enters your eyes. Those feelings of happiness and contentedness you get when hiking a beautiful mountain on a sunny day aren’t just in your head; they’re in your body.
Depression is linked to a lack of serotonin, and people with other depressive disorders, not just SAD, can experience an increase in their symptoms during the winter.
Studies have shown that serotonin levels drop faster in people with SAD. Meaning people with this condition are more susceptible to seasonal changes, experiencing greater fluctuations in serotonin levels throughout the year. Many drugs and therapies aim to supplement natural serotonin levels with varying degrees of success.
Lack of vitamin D
Studies suggest that vitamin D levels in those with SAD and other depressive disorders are often lower than control groups with no diagnosed depression.
Researchers have found that vitamin D and sunshine may play an even more integral role in mental health than previously thought. One study, published in the journal Medical Hypothesis by Alan Stewart of the College of Education at the University of Georgia, presents a possible cause and effect relationship between vitamin D deficiency and SAD.
Stewart says, “studies show there is a lag of about eight weeks between the peak in intensity of ultraviolet (UV) radiation and the onset of SAD, and this correlates with the time it takes for UV radiation to be processed by the body into vitamin D.”
Plus, vitamin D helps boost serotonin levels. Therefore, a vitamin D deficiency could mean less serotonin in the body. Lack of vitamin D also contributes to cardiovascular disease, another risk factor for depression.
Too much melatonin
There is some evidence supporting the theory that people with SAD produce an overabundance of the sleep hormone melatonin. This can cause daytime sleepiness, brain fog, and feelings of depression.
Disruption of the circadian rhythm
Vitamin D, serotonin, and melatonin are intrinsically linked to the circadian rhythm, sunlight, sleep, and mood. It makes sense that researchers have been unable to determine a clear cause of SAD, as all of these factors work in conjunction to create imbalance and disruption in the brain.
Risk factors for seasonal affective disorder
Location
Populations further from the equator have a higher rate of SAD. This is likely due to long winters, short summers, and lack of sunlight. One survey found that the incidence of SAD at the latitude of New Hamshire was 10 percent, while in Florida, it was only one percent. Many people experience fewer symptoms when they move to a sunnier locale.
Gender
If you are a woman, you are at a higher risk of developing SAD. Experts aren’t sure why but agree that it likely has something to do with hormonal mood associations. Fluctuating levels of estrogen could impact serotonin production.
Of course, this doesn’t mean you’re guaranteed to develop SAD if you’re female, but it is essential to be on the lookout for symptoms so that you can take steps to reduce the effects and get help if needed.
What about the winter blues?
Though only an estimated four to six percent of Americans have been diagnosed with seasonal affective disorder, millions of others suffer from a more mild version of the seasonal mood disorder. This is often called the “winter blues.” According to studies, most individuals experience decreased energy, altered mood, fatigue, and altered appetite during the winter months.
This hibernation mentality often leads to unhealthy lifestyle choices, which could also contribute to a negative mental state. Many of the tools for managing SAD can help you battle a bout of winter blues and keep you positive and healthy.
How to manage SAD

Most SAD symptoms go away by themselves as the days lengthen and the sun warms the earth. However, rather than hunkering down and waiting for spring, take steps to regain control of your life, boost your mood, and, perhaps, even enjoy the winter.
Remember, SAD is a depressive disorder, so it won’t necessarily ever go away for good. Talk to your doctor as they can provide resources to help you work through your symptoms.
Taking steps to look after yourself and prioritize your mental health is essential. A little self-care and sunshine go a long way.
Light therapy
Though the best light therapy is spending time in the sunlight, those in climates further from the equator (who have higher rates of SAD) have very weak sunlight during the winter months. The use of a lightbox or vitamin D lamp for around 20 minutes each day is a safe, effective way to mimic the healing effects of the sun, boost vitamin D levels, and reduce SAD symptoms.
In the early 1980s, Norman E. Rosenthal, M.D. first made the connection between the dark days of winter and his seasonal cycles of depression. This led to further research, and he and his associates at the National Institute of Mental Health (NIMH) named and defined seasonal affective disorder.
They believed that lack of light during the winter was responsible for this change in mood and performed a placebo-controlled study documenting the effects of light therapy on people with seasonal-related depression. They found that light therapy produced an antidepressive effect within a few days of starting treatment.
Over the last 40 years, other studies have continually documented positive results from this simple yet effective treatment. Continue light therapy through the winter until the sun shines brightly again.
Cognitive-behavioral therapy
Psychotherapy or “talk therapy” involves working with a trusted mental health professional to work through triggers and process thoughts and emotions. Though this treatment takes time, patience, and dedication, it is often associated with the best long-term results and could help you manage SAD in the future.
A note on antidepressants
Doctors love to prescribe antidepressants before trying other therapies with far fewer side effects. Though prescription drugs could be beneficial in managing severe SAD cases, they come with risks and should be used with extreme caution. Speak with your holistic doctor about natural alternatives before starting antidepressants.
Other tips:
- Exercise outdoors
- Move your desk closer to a window
- Confide in someone
- Be patient with yourself
- Tackle small tasks first
- Avoid alcohol and drugs
- Eat an organic, 100 Year Heart Diet
- Develop a healthy sleep routine
- Try vitamin D supplements
- Prepare early. Start managing symptoms in the fall
- Use a daylight-stimulating alarm clock
- Find an outdoor winter activity you enjoy
- Diffuse calming essential oils like lavender
- Keep a gratitude journal
- Keep your blinds open during the day to let in natural light
Shedding light on the situation
Get out in the sun, purchase a light therapy box, talk to someone, seek treatment. You don’t have to struggle through the winter in silence. If you have seasonal affective disorder, be proactive and get ahead of the change in the seasons during fall, mentally and physically preparing for winter by eating a healthy diet, exercising regularly, and getting plenty of sunshine as often as you can
Eat Well · Live Well · Think Well
Medical Review 2022: Dr. Lauren Lattanza NMD