What is Seasonal Affective Disorder (SAD)

Seasonal affective disorder is a type of depression. It is when you feel depressed at specific times of the year. SAD is most common during late fall and winter when the days are shorter and most people spend less time outdoors.

This is why Seasonal Affective Disorder is also known as the “winter blues.” SAD occurs less commonly in the spring or summer.

SAD is a disorder of mood (not an affect disorder) characterized by persistent depressive symptoms with an onset related to environmental changes in day–night length—short days and long nights—the incidence of which is more common farther from the equator. 

Seasonal Affective Disorder can be mild to severe, and it can interfere with work, school, relationships, and normal daily activities.

What are the causes of Seasonal Affective Disorder?

The cause of this condition is not known. It may be related to changes in brain chemistry that are caused by having less exposure to daylight.

What increases the risk?

You are more likely to develop Seasonal Affective Disorder condition if:

• You are female.
• You live far north or far south of the equator. These areas get less sunlight and have longer winter seasons.
• You have a personal history of depression or bipolar disorder.
• You have a family history of mental health conditions.

What are the symptoms of Seasonal Affective Disorder?

Symptoms of this condition include:

• Depressed mood, which may involve:
  • Feeling sad or teary.
  • Having crying spells.
• Irritability.
• Trouble sleeping, or sleeping more than usual.
• Loss of interest in activities that you usually enjoy.
• Feelings of guilt or worthlessness.
• Restlessness or loss of energy.
• Difficulty concentrating, remembering, or making decisions.
• Significant change in appetite or weight.
• Thinking about self-harm or attempting suicide.

Symptoms associated with the winter pattern of SAD include:

• Overeating or craving sweet foods.
• Weight gain.
• Avoiding social situations (social withdrawal), or feeling like “hibernating.”
• Sleeping more than usual.

Symptoms associated with the less common summer pattern of SAD include:

• Loss of appetite.
• Weight loss.
• Trouble sleeping.
• Episodes of violent behavior (in severe cases).

How is Seasonal Affective Disorder diagnosed?

This condition is usually diagnosed through an assessment with your health care provider. You will be asked about your moods, thoughts, and behaviors. You will also be asked about your medical history, any major life changes, and any medicines and substances that you use.

You may have a physical exam and blood tests to rule out other possible causes of your symptoms. You may be referred to a mental health specialist for more evaluation.

How is this treated?

Treatment for this condition may include:

• Light therapy. This therapy involves sitting in front of a light source for 15–30 minutes every day. The light source may be:
  • A light box.
  • A dawn simulator or sunrise clock. This is a timer-activated light source that copies the sunrise by slowly becoming brighter. This can help to activate your body’s internal clock.
• Antidepressant medicine.
• Cognitive behavioral therapy (CBT). CBT is a form of talk therapy that helps to identify and change negative thoughts that are associated with SAD.
• Changes to your dietary, exercise, or sleeping habits. A healthy lifestyle may help to prevent or relieve symptoms.

SAD treatments include appropriately timed bright light therapy and melatonin.

Follow these instructions at home:

Medicines

• Take over-the-counter and prescription medicines only as told by your healthcare provider.
• If you are taking antidepressant medicines, ask your health care provider what side effects you should be aware of.
• Talk with your health care provider before you start taking any new prescription or over-the-counter medicines, herbs, or supplements.

Lifestyle

• Eat a healthy diet that includes fruits and vegetables, whole grains, and lean proteins.
• Get plenty of sleep. To improve your sleep, make sure you:
  • Keep your bedroom dark and cool.
  • Go to sleep and wake up at about the same time every day.
  • Do not keep screens (such as a TV or smartphone) in your bedroom. Limit your screen time starting a few hours before bedtime.
• Exercise regularly.
• Limit alcohol and caffeine as told by your health care provider.

General instructions

• Make your home and work environment as sunny or bright as possible. Open window blinds and move furniture closer to windows.
• Spend as much time outside as possible.
• Use light therapy for 15–30 minutes every day, or as often as directed.
• Attend CBT therapy sessions as directed.
• Keep all follow-up visits as told by your health care provider and therapist. This is important.

Contact a health care provider if:

• Your symptoms do not get better or they get worse.
• You have trouble taking care of yourself.
• You are using drugs or alcohol to cope with your symptoms.
• You have side effects from medicines.

Get help right away if:

• You have thoughts about hurting yourself or others.

If you ever feel like you may hurt yourself or others, or have thoughts about taking your own life, get help right away. You can go to your nearest emergency department or call:

• Your local emergency services (911 in the U.S.).
• A suicide crisis helpline, such as the National Suicide Prevention Lifeline at 1-800-273-8255. This is open 24 hours a day.

Summary

• Seasonal affective disorder (SAD) is a type of depression that is associated with specific times of the year (usually fall and winter).
• This condition may be treated with light therapy, talk therapy, and antidepressant medicines.
• To help treat your condition, take good care of yourself and make home and work as sunny and bright as possible.
• Seek help right away if you have thoughts about hurting yourself or others.