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Seasonal Affective Disorder (SAD)

Recognizing and Treating Seasonal Depression and the Winter Blues

Dealing with Depression

The shorter days and colder weather of winter can make anyone feel down, especially if you live a long way from the equator. The reduced light, warmth, and color of winter can leave you feeling melancholy, irritable, or tired. But if these feelings recur each year, make it tough to function during the winter months, and then subside in spring or early summer, you may be suffering from seasonal affective disorder (SAD). Seasonal depression can affect your health, your relationships, and your everyday activities. But no matter how hopeless you feel, there are things you can do to keep your mood and life stable throughout the year.

What is seasonal affective disorder (SAD)?

Seasonal affective disorder (SAD) is a form of depression that occurs at the same time each year, usually in winter. Otherwise known as seasonal depression, SAD can affect your mood, sleep, appetite, and energy levels, taking a toll on all aspects of your life from your relationships and social life to work, school, and your sense of self-worth. You may feel like a completely different person to who you are in the summer: hopeless, sad, tense, or stressed, with no interest in friends or activities you normally love. While a less common form of the disorder causes depression during the summer months, SAD usually begins in fall or winter when the days become shorter and remains until the brighter days of spring or early summer.

SAD affects about 1% to 2% of the population, particularly women and young people, while a milder form of winter blues may affect as many 10 to 20 percent of people. Since the amount of winter daylight you receive changes the farther you are from the equator, SAD is most common in people who live at least 30 degrees latitude north or south (north of places such as Jacksonville, Florida, Austin, Texas, Cairo, Egypt, and Hangzhou, China, or south of Perth, Australia, Durban, South Africa, and Cordoba, Argentina). No matter where you live, though, or how dark and cold the winters, the good news is that, like other forms of depression, SAD is treatable. The more you understand about seasonal depression, the better equipped you’ll be to manage or even prevent the condition.

Could I have seasonal affective disorder (SAD)?

If some of these feelings seem to happen each year, have a real impact on your life, and improve during certain seasons, talk to your doctor, you may have seasonal affective disorder.

  • I feel like sleeping all the time, or I’m having trouble getting a good night’s sleep
  • I’m tired all the time, it makes it hard for me to carry out daily tasks
  • My appetite has changed, particularly more cravings for sugary and starchy foods
  • I’m gaining weight
  • I feel sad, guilty and down on myself
  • I feel hopeless
  • I’m irritable
  • I’m avoiding people or activities I used to enjoy
  • I feel tense and stressed
  • I’ve lost interest in sex and other physical contact

Source: BC Mental Health

Signs and symptoms of seasonal affective disorder

The signs and symptoms of seasonal affective disorder are the same as those for major depression. SAD is distinguished from depression by the remission of symptoms in the spring and summer months (or winter and fall in the case of summer SAD).

Common symptoms of seasonal depression include:

  • Depressed mood, low self-esteem
  • Loss of interest or pleasure in activities you used to enjoy
  • Feelings of sadness, hopelessness, and despair
  • Feeling angry, irritable, stressed, or anxious
  • Unexplained aches and pains
  • Changes in sleeping pattern
  • Appetite and weight changes
  • Difficulty concentrating
  • Fatigue and lack of energy; reduced sex drive
  • Use of drugs or alcohol for comfort

As with depression, the severity of SAD symptoms can vary from person to person—often depending on genetic vulnerability and geographic location. For many, the symptoms usually begin mildly at the start of fall and get progressively worse through the darkest days of winter. Then, by spring or early summer, the symptoms lift until you’re in remission and feel normal and healthy again.

To be clinically diagnosed with seasonal affective disorder, you need to have experienced these cyclical symptoms for two or more consecutive years. Regardless of the timing or persistence of your symptoms, if your depression feels overwhelming and is adversely affecting your life, it's time to seek help.

Seasonal changes in bipolar disorder

The changes in seasons can trigger mood changes in some people with bipolar disorder. Spring and summer may trigger symptoms of mania or hypomania, while the onset of fall and winter can bring on symptoms of depression. While the depression symptoms of SAD and bipolar disorder can look alike, there are significant differences, especially when it comes to treatment. To learn more about bipolar disorder, see Bipolar Disorder Signs and Symptoms.

If You Are Feeling Suicidal...

Whatever the season, when you’re feeling depressed your problems may not seem temporary—they can seem overwhelming and permanent. But you will feel better. If you are feeling suicidal, know that there are many people who want to support you during this difficult time, so please reach out for help.

Read Suicide Help or call 1-800-273-TALK in the U.S. or visit IASP or Suicide.org to find a helpline in your country.

Causes of seasonal affective disorder

While the exact causes of seasonal affective disorder are unclear, most theories attribute the disorder to the reduction of daylight hours in winter. The shorter days and reduced exposure to sunlight that occurs in winter are thought to affect the body by disrupting:

  • Circadian rhythms. Your body's internal clock or sleep-wake cycle responds to changes between light and dark to regulate your sleep, mood, and appetite. The longer nights and shorter days of winter can disrupt your internal clock—leaving you feeling groggy, disoriented, and sleepy at inconvenient times. 
  • Production of melatonin. When it’s dark, your brain produces the hormone melatonin to help you sleep and then sunlight during the day triggers the brain to stop melatonin production so you feel awake and alert. During the short days and long nights of winter, however, your body may produce too much melatonin, leaving you feeling drowsy and low on energy.
  • Production of serotonin. The reduced sunlight of winter can lower your body’s production of serotonin, a neurotransmitter that helps to regulate mood. A deficit may lead to depression and adversely affect your sleep, appetite, memory, and sexual desire.

Summer of SAD

The less common form of SAD, summer depression, begins in late spring or early summer and ends in fall. Instead of being attributed to shorter days and reduced sunlight, experts believe that summer SAD is caused by the opposite—longer days and increased heat and humidity, possibly even an upswing in seasonal allergies.

Many summer SAD symptoms are the same as those for winter depression, although there are some differences. The longer daylight hours and shorter nights mean that if you have summer SAD, you’re more likely to sleep too little rather than too much. To promote sleep, your doctor may suggest taking melatonin supplements to make up for your body’s lower production. Changing your sleeping patterns by going to bed earlier at night (as soon as it gets dark in some cases) and rising earlier in the morning can also help to reset your body’s circadian rhythms.

As with any form of depression, there can be many different causes and contributing factors for seasonal affective disorder. Always consult your doctor for an accurate diagnosis and see the lifestyle changes outlined below for help to boost your mood and manage your depression symptoms.

Risk factors

Seasonal affective disorder can affect anyone but is most common in people who live far north or south of the equator. This means you’ll experience less sunlight in the winter months and longer days during the summer. Other risk factors include:

  • Your gender. While 3 out of 4 sufferers of SAD are women, men often experience more severe symptoms.
  • Your age. In most cases, winter SAD is first diagnosed in people aged 18 to 30 and is less likely to occur as you get older.
  • Your family history. Having relatives who’ve experienced SAD or another type of depression puts you at greater risk. 

Self-help tips for seasonal affective disorder

Seasonal depression can make it hard to motivate yourself to make changes, but there are plenty of steps you can take to help yourself feel better. Recovery takes time but you’ll likely feel a little better each day. By adopting healthy habits and scheduling fun and relaxation into your day, you can help lift the cloud of seasonal affective disorder and keep it from coming back.

Tip #1: Get as much natural sunlight as possible—it's free!

Whenever possible, get outside during daylight hours and expose yourself to the sun without wearing sunglasses (but never stare directly at the sun).

  • Take a short walk outdoors, have your coffee outside if you can stay warm enough.
  • Increase the amount of natural light in your home and workplace by opening blinds and drapes and sitting near windows.
  • Some people find that painting walls in lighter colors or using daylight simulation bulbs also helps combat winter SAD.

Tip #2: Exercise regularly—it can be as effective as medication

Regular exercise is a powerful way to fight seasonal depression, especially if you’re able to exercise outside in natural daylight.

  • Regular exercise can boost serotonin, endorphins, and other feel-good brain chemicals. In fact, exercise can treat mild to moderate depression as effectively as antidepressant medication.
  • Exercise can also help to improve your sleep and boost your self-esteem.
  • Aim for 30 to 60 minutes of activity on most days. Even something as simple as walking a dog, for example, can be good exercise for you and the animal, as well as a great way to get outdoors and interact with other people.

Tip #3: Reach out to family and friends—and let them help

Close relationships are vital in reducing isolation and helping you manage SAD. Participate in social activities, even if you don’t feel like it. It may feel more comfortable to retreat into your shell, but being around other people will boost your mood. Even if you’ve retreated from relationships that were once important to you, make the effort to reconnect or start new relationships.

  • Call or email an old friend to meet for coffee. Or reach out to someone new—a work colleague or neighbor, for example. Most of us feel awkward about reaching out, but be the one to break the ice.
  • Join a support group for depression. Sometimes, just talking about what you’re going through can help you feel better. Being with others who are facing the same problems can help reduce your sense of isolation and provide inspiration to make positive changes.
  • Meet new people with a common interest by taking a class, joining a club, or enrolling in a special interest group that meets on a regular basis. Whatever you choose, make sure it’s something that’s fun for you.
  • Volunteer your time. Helping others is one of the best ways to feel better about yourself, expand your social network, and overcome SAD.

Tip #4: Eat the right diet

Eating small, well-balanced meals throughout the day, with plenty of fresh fruit and vegetables, will help you keep your energy up and minimize mood swings.

  • While the symptoms of SAD can make you crave sugary foods and simple carbohydrates, such as pasta and white bread, complex carbohydrates are a better choice. Foods such as oatmeal, whole grain bread, brown rice, and bananas can boost your feel-good serotonin levels without the subsequent sugar crash.
  • Foods rich in certain omega-3 fats—such as oily fish, walnuts, soybeans, and flaxseeds—can also improve your mood and may even boost the effectiveness of antidepressant medication.

Tip #5: Take steps to deal with stress—by making time for fun

Whatever the time of year, too much stress can exacerbate or even trigger depression. Figure out the things in your life that stress you out, such as work overload or unsupportive relationships, and make a plan to avoid them or minimize their impact.

  • Practicing daily relaxation techniques can help you manage stress, reduce negative emotions such as anger and fear, and boost feelings of joy and well-being. Try yoga, meditation, or progressive muscle relaxation.
  • Do something you enjoy every day. Having fun is a great stress buster, so make time for leisure activities that bring you joy, whether it be painting, playing the piano, working on your car, or simply hanging out with friends.

Treatment for seasonal affective disorder

While your doctor may also suggest treatment such as medication or psychotherapy, the mainstay of winter SAD treatment is light therapy, otherwise known as phototherapy. Light therapy aims to replace the missing daylight of winter by exposing you to bright light that mimics natural outdoor light. Daily exposure can suppress the brain’s secretion of melatonin to help you feel more awake and alert, less drowsy and melancholy.

Light therapy has been shown to be effective in up to 85 percent of SAD cases. However, the timing and length of exposure needed can vary according to your symptoms and circadian rhythm, so you’ll need guidance from your doctor or mental health professional to find the right dosage. Your doctor or therapist can also help you choose a light therapy product that's both effective and safe.

Light therapy has to be continued daily throughout the winter months to be effective. Starting light therapy before the onset of symptoms in the fall may even help prevent seasonal affective disorder.

There are two different ways of administering light therapy.

  • A light box delivers light that with up to ten times the intensity of normal domestic lighting. In most cases, you simply sit about 12 inches in front of a 10,000 lux light box for 15 to 30 minutes each morning. The light box emits a controlled amount of white light, with harmful ultraviolet (UV) rays filtered out. While the light needs to enter the eyes, you shouldn’t stare directly at the light box, but rather continue your morning routine, such as eating breakfast, reading the newspaper or working at the computer. Most people notice an improvement in their SAD symptoms after a few days and experience the full antidepressant effect in about two weeks.
  • A dawn simulator is a device that gradually increases the amount of light in your bedroom in the morning to simulate the rising sun and wake you up. The light gradually increases, just as natural sunlight does, over a period of 30 to 45 minutes. Instead of waking in darkness, you wake to what looks like a sunny morning. This can help reset your circadian rhythm and improve your mood. While light boxes may trigger hypomania or mania in those with bipolar disorder, there is no such risk with a dawn simulator.

While tanning beds generate sufficient light, they should never be used to treat SAD as the UV rays they produce can be harmful to the skin and eyes.

Light therapy for seasonal affective disorder: What you need to know

Light therapy involves daily sessions of sitting close to a special light source that is far more intense than normal indoor light. Some people feel better after only one light treatment, but most people require at least a few days of treatment, and some need several weeks. You do not need a prescription to purchase a light box to treat SAD; however, it’s best to work with a professional to monitor the benefits of the treatment.

Some SAD light boxes look like medical equipment, while others are more like regular table lamps. The prices vary. Although professional groups and government agencies endorse light therapy, your insurance company in the U.S. may balk. If you are counting on coverage, you better check first.

There are few side effects to light therapy, but you should be aware of the following potential problems:

  • Mild anxiety, jitteriness, headaches, early awakening, or eyestrain can occur.
  • There is evidence that light therapy can trigger a manic episode in people who are vulnerable.
  • While there is no proof that light therapy can aggravate an eye problem, you should still discuss any eye disease with your doctor before starting light therapy. Likewise, since rashes can result, let your doctor know about any skin conditions.
  • Some drugs or herbs (for example, St. John’s wort) can make you sensitive to light.

Adapted with permission from Understanding Depression, a special health report published by Harvard Health Publications.

Medication and psychotherapy for seasonal affective disorder

While light therapy is often a highly effective treatment for SAD or the winter blues, it doesn’t work for everyone. If that’s the case, don’t despair, there are other effective treatment options available and plenty of self-help techniques to help you feel better.

  • Cognitive behavioral therapy (CBT) can be highly beneficial for people with seasonal depression. The right therapist can help you curb negative thoughts, attitudes, and behaviors that make the disorder worse and help you learn how to manage symptoms and deal with stress in healthy ways. For many people, CBT can be as effective at treating seasonal affective disorder as light therapy or antidepressants, but without any risky side-effects.
  • Medication. If light therapy doesn’t work for you, your doctor may suggest antidepressant medication. SSRI antidepressants work by acting on serotonin levels in the brain to reduce SAD symptoms. In the U.S., the FDA has specifically approved the drug bupropion (Wellbutrin) to treat seasonal affective disorder. However, as with all antidepressants, there may be adverse side effects, including a number of safety concerns specific to children and young adults. It’s important to weigh the benefits against the risks before starting on medication.

Whatever treatment plan you settle on, it’s important to combine it with self-help techniques to help manage your depression symptoms and even help prevent seasonal affective disorder returning next year.


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Resources and references

Seasonal affective disorder: causes and treatment

Seasonal Affective Disorder – Outlines the diagnostic criteria for winter SAD as well as tips on treatment and how to cope with symptoms. (BC Mental Health)

Causes of seasonal affective disorder – Discusses how the amount of sunlight you receive affects some of your body's hormones and the chemicals in the brain. (NHS)

Seasonal affective disorder: When winter brings the blues – Causes and treatment for winter SAD. (Harvard Health Publications)

Seasonal affective disorder (SAD) – Outlines the symptoms of winter and summer SAD, as well as treatment and self-help tips. (Mayo Clinic)

Light therapy for seasonal affective disorder

Seasonal affective disorder: bring on the light – Blog about the value of bright light therapy and how to choose a light box. (Harvard Health Publications)

Light Therapies for Depression – Discusses using and buying a dawn simulator or light box, including price guides and comparison of different units. (PsychEducation.org)

Authors: Lawrence Robinson and Jeanne Segal, Ph.D. Last updated: April 2016.