What is seasonal affective disorder?

A woman sitting outside on her porch

Did you notice you always feel sad or depressed during the winter? You may have a case of the “winter blues,” also known as seasonal affective disorder (SAD).

SAD is a common condition that affects many people, especially those who live farther north because of the lack of sunlight. People who experience SAD during the spring and summer months (summer-pattern SAD or summer depression) are less common.¹ CenterWell Pharmacy® is here to help you find the support you need.

The causes of seasonal affective disorder

The specific cause of SAD is unknown.² However, SAD is linked to a biochemical imbalance in the brain prompted by less sunlight in winter.³

Some causes may include:

Your internal clock—The lack of sunlight may disrupt your body’s internal clock.

Serotonin levels—Serotonin is a chemical in your brain that affects your mood. Reduced sunlight can cause your serotonin levels to drop, which may trigger depression.

Melatonin levels—Your body’s level of melatonin plays a role in your sleep patterns and mood. The change in season may affect your mood and how you sleep.

SAD is more common in people with major depressive or bipolar disorders, a family history of SAD and those who live farther north from the equator.²

Symptoms to watch for

People with SAD during the fall and winter may experience:²

  • Oversleeping
  • Overeating
  • Weight gain
  • Low energy
  • Tiredness

People with SAD during the spring and summer may experience:²

  • Trouble sleeping
  • Lack of appetite
  • Weight loss
  • Agitation
  • Anxiety

If you’re experiencing the symptoms above, speak with your healthcare provider, especially if you start to feel down for days at a time or don't feel motivated for things you usually enjoy. It's important to treat SAD before it leads to other problems.

Treatments available for seasonal affective disorder

After speaking with your healthcare provider about your symptoms, they may recommend a treatment that falls into 4 categories, which may be used alone or in combination:¹

Light therapy: This therapy exposes you to bright light every day for about 30–45 minutes to make up for the lack of natural light.

Psychotherapy: Cognitive behavioral therapy helps you learn how to handle difficult situations and replace negative thoughts with positive ones.

Vitamin D: Taking a vitamin D supplement may help improve your symptoms—and the supplements are easy to find at your local pharmacy or our OTC store (if your Humana plan has an OTC benefit).

Antidepressant medications: Because SAD is a form of depression, taking a type of medication called selective serotonin reuptake inhibitors (SSRIs), including Prozac® (fluoxetine), Celexa® (citalopram) or Zoloft® (sertraline), can help enhance your mood.

How CenterWell Pharmacy can help

SAD is a serious condition, but help is available so you can start feeling better. First, speak with your healthcare provider to see if you may benefit from antidepressant medication. If you're a CenterWell Senior Primary Care patient or would like to become one, our doctors can help provide the care you need.

If your healthcare provider prescribes you a new medication, you can fill your prescription on our website. When you do, you'll save a trip to the pharmacy with secure home delivery.

And if you have questions about your prescription or need help, you can live chat with us or call us at 800-379-0092 (TTY: 711), Monday – Friday, 8 a.m. – 11 p.m., and Saturday, 8 a.m. – 6:30 p.m., Eastern time.


  1. “Seasonal Affective Disorder,” National Institute of Mental Health, last accessed November 30, 2023, https://www.nimh.nih.gov/health/publications/seasonal-affective-disorder.
  2. “Seasonal affective disorder (SAD),” Mayo Clinic, last accessed November 30, 2023, https://www.mayoclinic.org/diseases-conditions/seasonal-affective-disorder/symptoms-causes/syc-20364651.

Disclaimer: This material is provided for informational use only and should not be construed as medical advice or used in place of consulting a licensed medical professional. You should consult with your doctor to determine what is right for you

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