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Seasonal affective disorder: definition, symptoms, causes, and treatments

Reading time: 15 mins
Seasonal affective disorder: definition, symptoms, causes, and treatments

Seasonal affective disorder, or SAD, is a form of depression whose symptoms only become more apparent during certain times of the year. Changes in one’s mood and behavior can be significant and overwhelming, ultimately affecting a person’s ability to perform routine activities.

The symptoms of seasonal affective disorder include feeling drained most of the day, oversleeping, lack of energy, difficulty focusing, feelings of worthlessness, losing interest in things previously enjoyed, overeating, and thoughts of death or suicide.

The causes of SAD include our biological clock, serotonin levels, and melatonin levels.

The treatments for seasonal depression are light therapy, psychotherapy, and medications.

What is seasonal affective disorder?

Seasonal affective disorder is a type of depression tied to seasonal changes, and starts and finishes roughly at the same periods each year. Its symptoms resemble those of normal depression, but they tend to come and go with the seasons.

Additionally, just like the symptoms of depression, the symptoms of seasonal affective disorder can also be highly distressing and can interfere with one’s daily life.

How common is seasonal affective disorder?

Seasonal affective disorder is common, and it affects around five percent of U.S. adults, with symptoms lasting for about 40 percent of the year, according to an article entitled, “Seasonal Affective Disorder (SAD)” published in the American Psychiatric Association.

Another article entitled, “Seasonal Depression (Seasonal Affective Disorder)” from Cleveland Clinic also states that SAD tends to be more common in women than men, although the reason is unclear to researchers.

When does a seasonal affective disorder begin?

Seasonal affective disorder begins in the fall and persists until winter before symptoms start to improve in the spring and summer and soon disappears; this is called winter-pattern SAD or winter depression and is experienced by most people who have the disorder.

Although less common, symptoms can also manifest in the spring and summer; this is known as summer-pattern SAD or summer depression.

What are the symptoms of seasonal affective disorder?

The symptoms of seasonal affective disorder occur during certain seasons of the year. The symptoms of seasonal affective disorder are listed below.

  • Feeling drained, depressed, or down most of the day
  • Having issues with excessive sleep
  • Feeling lethargic and low in energy
  • Having trouble staying focused
  • Having a sense of worthlessness or remorse
  • Losing interest in things you used to enjoy
  • Having cravings for carbohydrates, eating too much, and gaining weight
  • Having the desire to end one’s life

1. Feeling drained, depressed, or down most of the day

Feeling drained, depressed, or down for the most part of the day means you feel sad most of the time, most days. While it is normal to be sad from time to time, persistent feelings of sadness and low mood can negatively impact one’s motivation to do their basic daily routines.

Persistent low mood becomes a symptom of winter depression by affecting how one feels, thinks, and acts. This profound feeling of sadness also stops an individual from doing normal activities.

Feeling down most of the day is a sign of SAD because it is a defining feature of depression and most of its forms.

Finally, this symptom can be identified if one’s feelings of sadness start to interfere with their daily functioning and change how they experience enjoyment.

2. Having issues with excessive sleep

a man sleeping on office floor.

Having issues with excessive sleep refer to a common symptom of seasonal affective disorder in which an individual sleeps too much as a way to cope with stress, low mood, or other negative emotions.

Oversleeping becomes a symptom of SAD if one intentionally spends most of their day sleeping in an attempt to escape unwanted negative feelings and to not be reminded of how their symptoms are affecting their lives.

Excessive sleep is a sign of seasonal depression because this experience is commonly seen in most people with the condition. This results in severe daytime sleepiness and low mood, which can affect the ability to do daily tasks.

Oversleeping can be identified by looking out for its signs, such as sleeping more hours than usual, low productivity, excessive daytime sleepiness, low energy, and memory problems.

3. Feeling lethargic and low in energy

Feeling lethargic and low in energy means that you are exhausted, and you lack the energy or mental alertness to deal with your surroundings. It can also result from sleep disturbances caused by seasonal affective disorder.

Fatigue becomes a cause for concern as a warning sign of SAD when it lasts for two weeks or more, and it starts impacting your daily life. For instance, in some people, fatigue caused by winter depression can result in poor concentration.

Lethargy is considered one of the symptoms of seasonal affective disorder because it is a common occurrence in those living with the condition. It is one of the most common feelings that SAD can make someone feel, and feelings of tiredness and low energy can also make the disorder worse.

Lethargy can be spotted on a loved one by watching out for signs, such as sluggishness, reduced ability to think, decreased mental alertness, changes in mood, low energy, and lack of motivation.

4. Having trouble staying focused

Having trouble staying focused is a symptom of seasonal depression that involves the inability to concentrate and get easily distracted. When you have this symptom, you find it challenging to stay focused on a certain task because your disorder interferes with your goal.

Loss of concentration becomes a symptom of SAD when its effects become so serious that it results in misunderstandings at work, school, or home. For instance, someone with seasonal depression might find that they can’t focus when they are given directions at work or when a family member is talking to them.

With loved ones, this kind of distraction may be mistaken as lack of consideration for what others are saying.

Difficulty focusing is regarded as one of the signs of SAD because research suggests that the capacity to process information quickly and effectively is hindered in people living with depression, as stated by an article entitled, “Depression, Memory Loss, and Concentration” from Everyday Health.

One can identify if a loved one is having trouble concentrating by looking for signs, such as restlessness, difficulty making decisions, trouble remembering things that only happened recently, making careless mistakes, lack of energy, and not being able to accomplish normal daily tasks.

5. Having a sense of worthlessness or remorse

Having a sense of worthlessness or feelings of remorse means that you feel useless and that you have nothing worthwhile to offer to the world, and you may also feel guilty because you think you are being a burden to others by having seasonal depression.

Feelings of guilt and worthlessness become a symptom of SAD when they start to distort your sense of self and make you believe negative things about yourself. For instance, you may think that you are not good enough, or you cannot forgive yourself for a past mistake.

Feeling a sense of worthlessness or remorse is regarded as a sign of seasonal depression because they typically stem from low self-esteem, which is a known risk factor for depression.

Feelings of guilt and worthlessness can be identified by being able to spot its symptoms, including hopelessness, lack of interest in activities once enjoyed, changes in mood, increased frustration, and low energy.

6. Losing interest in things you used to enjoy

Losing interest in things once enjoyed, also known as anhedonia, is defined as the inability to feel pleasure from certain activities you engaged a lot in before. Seasonal affective disorder can easily make someone disinterested in many things, even those they used to enjoy.

Loss of interest in everything becomes an indicator of SAD when it becomes too overwhelming and far-reaching that it negatively affects your productivity at school or work and your relationship with friends and family.

Anhedonia is considered one of the symptoms of SAD because it is a core feature of the condition, and it can be so serious that it diminishes one’s quality of life.

Lastly, noticing if someone is struggling with anhedonia by watching out for its signs, including social withdrawal, inability to feel pleasure from daily activities, loss of libido, pulling away from current relationships, and reduced interest in previous hobbies.

7. Having cravings for carbohydrates, eating too much, and gaining weight

Carbohydrate craving refers to the tendency of individuals suffering from winter depression to be drawn to carbohydrate-rich or sugary foods because they increase the production of serotonin, which is our body’s “feel-good” chemical.

Carb cravings become a symptom of SAD when they become unhealthy and people over-load on carbohydrates that they gain weight and have other health issues due to an unhealthy diet.

It is also regarded as an indicator of seasonal depression because those with SAD are particularly vulnerable to overloading on carbohydrates in an attempt to self-medicate and make themselves feel better.

Carb cravings can be identified in people with SAD by looking out for common signs, such as strong carb cravings when feeling unpleasant, low energy, brain fog, headaches, mood swings, and weight gain.

8. Having the desire to end one’s life

Having the desire to end one’s life means that a person may be preoccupied with thoughts of self-harm or suicide. They may spend a huge amount of time thinking of death, dying, and suicidal plans.

According to a population-based study about how seasonal changes in mood and behavior contribute to suicidality and worthlessness published in June 2022 in the Journal of Psychiatric Research, the problems experienced by individuals with SAD because of the seasonal variations in mood and behavior are linked to suicidal thoughts and worthlessness, hence how thoughts of suicide become a symptom of the condition.

Suicidal thoughts are regarded as a sign of seasonal depression because they are often a result of serious mood changes that occur in a seasonal pattern in those with winter depression.

One can recognize suicidal behaviors in an individual by watching out for its warning signs, including extreme mood swings, frequent thoughts about death, dying, or violence, talking about taking their own life, personality changes, and saying goodbye as if it’s the last time you’ll see them.

What are the causes of seasonal affective disorder?

The causes of seasonal affective disorder include theories that may come into play in the development of the condition. The causes of seasonal affective disorder are listed below.

  • Biological clock (circadian rhythm)
  • Serotonin levels
  • Melatonin levels

1. Biological clock (circadian rhythm)

According to a book penned by Reddy S et al., entitled, “Physiology, Circadian Rhythm” published in StatPearls, the 24-hour internal clock in our brains known as the circadian rhythm controls cycles of alertness and slumber by adjusting to variations in environmental light.

Because circadian rhythms are tied to the cycle of day and night, the decreased sunlight affects the biological clock of those with SAD, specifically causing winter depression.

The circadian rhythm being out of sync is one cause of seasonal affective disorder because changes in our natural light-dark cycle can disrupt the body’s internal clock and lead to the symptoms of SAD, including low mood and energy levels.

2. Serotonin levels

Serotonin is a neurotransmitter responsible for digesting, sleeping, healing, and regulating mood. A normal serotonin level helps you feel more emotionally stable and focused.

That said, low serotonin levels can become a cause of seasonal mood disorder by limiting the body’s ability to work properly in controlling one’s mood. Low serotonin activity has long been linked to a range of mental health problems, such as anxiety, depression, and post-traumatic stress disorder (PTSD).

Finally, serotonin deficiency is considered a cause of seasonal depression because it is the body’s natural “feel-good” neurotransmitter, therefore inadequate amounts of this chemical could negatively affect how we maintain our mood and our thinking process.

3. Melatonin levels

An article entitled, “Melatonin: What You Need to Know,” from the National Center for Complementary and Integrative Health states that the hormone melatonin is released by the brain in reaction to darkness. It aids in sleep as well as the timing of your circadian rhythms.

However, according to a 2015 overview of assessment and treatment approaches on seasonal affective disorder published in Depression Research and Treatment, people suffering from SAD may struggle with melatonin overproduction. The pineal gland releases the hormone melatonin, which makes people drowsy in response to darkness.

Lastly, melatonin is also considered a cause of symptoms of winter depression because shorter and darker days in the winter can stimulate the pineal gland to generate the hormone even during the day, resulting in melatonin overproduction disrupting circadian rhythms causing atypical depressive symptoms, like increase in sleepiness or tiredness, particularly during the winter, as stated by a 2022 article entitled, “Melatonin And Seasonal Affective Disorder: How Is It Linked? From HealthMatch.

What can I expect from seasonal affective disorder?

what to expect from seasonal affective disorder.

With seasonal affective disorder, you can expect to experience symptoms that tend to be more apparent during the winter season, such as continuously feeling depressed throughout the day almost daily, losing interest in activities previously enjoyed, appetite or weight changes, oversleeping, agitation, low energy, poor concentration, and suicidal thoughts.

On the other hand, according to an article entitled, “Seasonal Affective Disorder” published in the National Institute of Mental Health, individuals who suffer from summer-pattern SAD may expect to have symptoms like difficulty sleeping, poor appetite which may result in weight loss, violent behaviors, restlessness, agitation and anxiety.

Who is at risk for seasonal affective disorder?

Certain people are at a higher risk of developing seasonal affective disorder, including those with a family history of the condition or other types of depression, individuals who live far north or south of the equator, those who suffer from another mood disorder, and people with low vitamin D levels.

Genetic factors play a role in the development of SAD, so having blood relatives with SAD or other types of depression can increase one’s likelihood of developing SAD themselves.

Additionally, individuals who live far north or south of the equator are more likely to experience SAD, and the condition gets worse the further one is from the equator. This might be brought on by reduced amounts of sunlight in the winter and longer, sunnier days in the summer.

Those who already suffer from another mood disorder, such as major depression or bipolar disorder, are also more likely to have SAD than other people who do not live with these mental health conditions.

Finally, people with low levels of vitamin D – which have been shown to help encourage serotonin production – are at an increased risk of developing SAD because vitamin D deficiency also means less production of those feel-good chemicals.

How are seasonal affective disorders diagnosed?

Seasonal affective disorders are diagnosed by performing a psychological evaluation, which may involve a series of questions about the patient’s mood, lifestyle, any seasonal changes in mood and behavior, eating habits and sleep patterns, how their symptoms affect their daily functioning, and any personal or genetic vulnerabilities that may have contributed to the development of a depressive disorder.

The general practitioner may also conduct a physical examination to rule out any physical problem that may be causing symptoms of depression. According to a 2022 article entitled, “Diagnosis – Seasonal affective disorder (SAD)” from the NHS (National Health Service), diagnosis of SAD can be confirmed if, for at least two years, your depression happens at the same time each year, with periods of remission in between.

What are the treatments available for seasonal affective disorder?

The treatments available for SAD may be used alone or in combination. The treatments available for seasonal affective disorder are listed below.

  • Light therapy
  • Psychotherapy
  • Medications

1. Light therapy

Light therapy, also called bright light therapy (BLT) or phototherapy, is a treatment involving the use of artificial light to improve different health conditions. In particular, light therapy for SAD involves sitting in front of a light box for at least 30 minutes to an hour after waking up each day.

This kind of treatment helps treat SAD by replicating natural daylight, thus deceiving the body into believing that it is a warmer month, which will induce serotonin production and reduce melatonin production, leading to an improvement in symptoms, as stated by a 2022 article from the NHS (National Health Service) entitled, “Treatment – Seasonal affective disorder (SAD).

Phototherapy is also considered one of the treatments for winter depression because it makes up for the lack of sunlight exposure that contributes to the symptoms of the condition.

In a health blog post entitled, “Light therapy: Not just for seasonal depression?” from Harvard Health Publishing, Dr. Richard S. Schwartz, associate professor of psychiatry at Harvard Medical School, states that the effectiveness of light treatment is comparable to that of antidepressant medicines or well-known psychotherapies like cognitive behavioral therapy for both seasonal and nonseasonal depression.

Patients generally report an improvement in symptoms within a few days to a few weeks of light therapy.

2. Psychotherapy

Psychotherapy refers to a wide array of treatment techniques that can aid in the management of mental health issues and emotional distress. Cognitive behavioral therapy (CBT) is a form of psychotherapy that is often used for people with SAD.

CBT helps treat seasonal affective disorder by challenging and eliminating any detrimental thought habits that may be aggravating one’s symptoms. It is also regarded as one of the most common treatments for winter depression because it teaches patients healthier ways to cope with SAD and manage stress related to the condition.

CBT has been proven to effectively treat SAD. In fact, a study by Kelly J. Rohan et al., published in The American Journal of Psychiatry in 2016, discussed a trial that contrasted using light therapy alone with using light therapy in conjunction with CBT. Results were favorable in both groups, but after a year, CBT patients fared significantly better than those who only received light therapy. Even after controlling for continuing therapy, further analysis showed that the CBT participants improved more.

Finally, CBT is a type of short-term therapy, often lasting between five and twenty sessions.

3. Medications

Medications are prescription drugs designed to treat a variety of health problems. Antidepressant medications called selective serotonin reuptake inhibitors (SSRIs) are used to treat SAD when symptoms arise because SAD, like other types of depression, is linked to abnormalities in serotonin function.

Antidepressants help treat seasonal depression by increasing serotonin levels in the brain, which can assist in improving one’s mood and energy levels. SSRIs are also considered one of the treatments for SAD because as their name suggests, they block the reabsorption or reuptake of serotonin, so you have more of those chemical messengers active in your brain, which play a crucial role in regulating your sleep, appetite, behavior, and mood.

According to researchers Nicole Praschak-Rieder, MD and Matthäus Willeit, MD in their study regarding the treatment of seasonal affective disorders published in 2003 in the journal Dialogues in Clinical Neuroscience, SSRI medications such as fluoxetine and sertraline have been shown to be beneficial in the treatment of SAD in multicenter, double-blind, randomized studies.

In general, it normally takes two to four weeks of use before SSRIs start to work, as stated by an article entitled, “Overview – Selective serotonin reuptake inhibitors (SSRIs)” from the NHS (National Health Service). Although experiencing minor side effects are normal with SSRIs, it is not recommended for anyone to quit taking the medications cold turkey, as these effects will often subside soon.

Can seasonal affective disorder be prevented?

No, seasonal affective disorder cannot be prevented. However, because SAD follows a seasonal pattern, patients with the condition may find relief from its symptoms by beginning the aforementioned treatments come fall.

One can also reduce their risk of developing SAD by focusing on healthy habits that are helpful in improving their overall well-being.

How to prevent having a seasonal affective disorder?
a woman hiding her face.

Although seasonal affective disorder is not completely preventable, there are coping strategies you can adapt in addition to your treatment plan. Here are some healthy lifestyle habits you can try to manage your symptoms.

  • Spend time outdoors: First, you can try spending some time outdoors to get that natural daylight that can help you feel better. Being outside in nature can also help you engage in physical activity and social contact.
  • Look after your physical health: Once you’re comfortable enough in spending some time in nature, you can also incorporate some degree of physical activity into your daily routine. You can start off small by taking a long walk or exercising for 30 minutes at least three times a week.
  • Connect with others: Third, you can connect with others by seeing your friends or family members who can help you feel supported. If you find this difficult, you can also try attending peer group sessions, where you can meet people who share similar experiences or feelings as you. Whatever it is you choose, establishing connection with others can help you feel a sense of belonging.
  • Get enough sleep: Fourth, you can set a regular sleeping pattern by establishing a routine around your bedtime and scheduling the times you get up and go to bed each day. You can also try avoiding screen time a few hours before sleeping or doing a relaxing activity to prepare you for bedtime.
  • Seek professional help: Lastly, even though taking steps to keep your symptoms at bay is helpful, you can always consider seeking professional help to aid you in your mental health concerns. After all, a licensed professional can get to the roots of your problem and give you a new perspective on how to deal with its symptoms.

How to help someone with seasonal affective disorder?

Feeling the urge to help a loved one suffering from SAD is only natural when you see them struggling with the condition. The ways on how to help someone with seasonal affective disorder are listed below.

  • Listen and let them know you are there: Not everyone is willing to open up about what they are struggling with, but letting them know that you are always available to listen whenever they are ready to talk about what’s bothering them is a big help for people with SAD. This lets them know that they are not alone in their struggle and gives them enough authority to make decisions on their own.
  • Change your mind about mental health: Educate yourself about the symptoms of SAD, avoid saying insensitive things, and unlearn any inaccurate beliefs you may have about mental health before. For instance, mentally ill people can’t just ‘snap out of it,’ and their condition is much more complex than you think. Saying such unhelpful statements can make them more harsh towards themselves than they already are.
  • Ask how you can help: Each individual’s experience with SAD is unique, so asking a loved one how you can help can make them feel supported. This gesture can also show them that they have someone to turn to whenever they feel overwhelmed by their symptoms.
  • Offer to plan helpful activities for them: Encourage your loved one to engage in pleasurable activities by planning ahead with them. You can schedule a vacation for both of you, or you can also plan a day of doing their favorite activities. Making sure that there are other people to offer them support can help increase their participation in these activities as well.
  • Take care of yourself, too: As a carer, it is also important to look after yourself, so you can look after others, too. Set healthy boundaries while taking care of your loved one, and be clear with them about what you can and cannot do to offer support. It is also essential to seek social support, so you can talk to others about your thoughts and feelings, too.

Is seasonal affective disorder a mental illness?

Yes, seasonal affective disorder is a mental illness recognized as a diagnosable condition in The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). It is identified by the psychiatry text as a type of depression formally known as Major Depressive Disorder with Seasonal Pattern.

What is the difference between seasonal affective disorder and bipolar disorder?

The key differences between seasonal affective disorder and bipolar disorder have something to do with the nature of their mood changes, the duration of episodes, age of onset, triggers, and treatment.

When it comes to the nature of their mood changes, seasonal affective disorder (SAD) symptoms often manifest in the fall and winter. On the other hand, bipolar disorder (BD) is characterized by severe mood swings that can occur anytime of the year and range from extreme highs (mania) to extreme lows (depression).

Another difference is the duration of episodes for each condition. While winter depression usually lasts for a few months, typically from late fall to early spring, episodes in bipolar disorder last for weeks or even months.

The age of onset also differs between SAD and BD. For SAD, symptoms typically develop in young adulthood, while signs of BD can develop at any age but often becomes more evident in adolescence or early adulthood.

On the other hand, their triggers may slightly differ as well. For instance, seasonal depression is frequently triggered by inadequate amounts of sunlight and changes in seasons, while bipolar disorder can be triggered by a more complex combination of factors, including stress, sleep disturbances, and even certain medications.

Finally, according to an article entitled, “Seasonal Affective Disorder and Bipolar Disorder: How Is It Linked?” from HealthMatch, the two conditions may differ on how they benefit from light therapy. While light therapy is a mainstay treatment of seasonal affective disorder, when it comes to bipolar disorder, light therapy may cause an increased risk of switching states from depressive episodes to mania.