How Seasonal Affective Disorder (SAD) Can Affect Diabetes

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How Seasonal Affective Disorder (SAD) Can Affect Diabetes

While many people wholeheartedly embrace the fall and winter months, others may dread the end of summer, knowing that dark days lie ahead. Seasonal affective disorder, or SAD, for short, affects about 5% of adults in the U.S. and can last about 40% of the year, according to the American Psychiatric Association. What exactly is SAD, and how might it impact people who have diabetes?

What is SAD?

“SAD is a type of depression characterized by its recurrent seasonal pattern, with symptoms lasting about 4 to 5 months per year,” says the National Institute of Mental Health. While many people can go through periods of time where they feel sad or not like themselves, people who start to feel down and blue in the fall and winter months (also called the “winter blues”) and who feel better in the spring when daylight hours are longer may have SAD. In some cases, people can get SAD in the late spring or early summer, ending in the fall.

What are symptoms of SAD?

Because SAD is a form of depression, the signs and symptoms of this condition are very similar to people with major depression. Not everyone with SAD will have all of the symptoms listed below.

  • Feeling depressed most of the day, nearly every day
  • Losing interest in activities that you used to enjoy
  • Changes in appetite or weight
  • Having problems sleeping
  • Feeling sluggish or agitated
  • Having low energy
  • Feeling hopeless or worthless
  • Having difficulty concentrating
  • Having frequent thoughts of death or suicide

With SAD that occurs during the winter, other symptoms can include:

  • Sleeping too much
  • Overeating, especially high-carb foods
  • Weight gain
  • Social withdrawal (“hibernating”)

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What causes SAD?

Researchers aren’t exactly sure what causes SAD, but some possibilities include:

  • A drop in serotonin levels. Serotonin is a brain neurotransmitter that affects mood. A lack of sunlight can lead to reduced serotonin levels that might trigger depression.
  • Too much melatonin. Melatonin is a hormone that regulates the sleep-wake cycle. Too much melatonin can increase sleepiness.
  • A disruption in circadian rhythm. Circadian rhythm, or biological clock, can be affected by a decrease in sunlight which, in turn, can trigger SAD.
  • •A lack of vitamin D. Vitamin D is thought to promote serotonin activity. Also, the body produces vitamin D from exposure to sunlight; with reduced sunlight in the winter months, people may have lower vitamin D levels, which can affect serotonin.

Having negative thoughts and feeling about the fall and winter months (including the anticipated stresses of the holidays) are common in people with SAD. These negative thoughts and feelings may not necessarily be a cause of SAD, but it’s a useful focus of treatment, says the National Institute of Mental Health.

Who’s at risk for SAD?

Women have a higher risk of developing SAD than men, and SAD occurs more often in younger adults than older adults. Other risk factors for SAD are:

  • Living in a northern climate, such as Alaska or New England, where daylight hours are shorter
  • Having a depressive or bipolar disorder
  • Having ADHD (attention deficit/hyperactivity disorder)
  • Having an eating disorder 
  • Having an anxiety or panic disorder
  • Having a family history of SAD

How is SAD treated?

There are various treatments for SAD. Your health care provider will work with you to decide what’s best for you. Treatment may include:

Light therapy

With light therapy, you sit in front of a very bright light box every day for 30-45 minutes, usually in the morning. The light is 20 times brighter than a regular light. Note that light therapy can trigger manic episodes in people who have bipolar disorder.

Talk therapy

Cognitive-behavioral therapy (CBT) is aimed at helping people learn how to cope with difficult situations and learn how to manage stress.


Antidepressant medication can help some people with SAD. Examples are selective serotonin reuptake inhibitors (SSRIs) and bupropion. You may need to try different medications to find one that works for you. Also, it can take several weeks to notice benefits.

Vitamin D

Vitamin D may be helpful in people with a vitamin deficiency.

Going outdoors

Spending time outdoors — even on cloudy days — can help you relieve stress and anxiety.

How does SAD affect diabetes?

Having SAD can impact how you take care of your diabetes, leading to higher blood sugars and A1Cs. Feeling down, especially during the winter months, can make it harder to practice self-care behaviors.

Shorter days and colder temperatures can make it challenging to go outside and to be active. Planning activity earlier in the day or switching to an indoor form of activity can help.

Having SAD might make it more likely to make less healthy choices and eat higher-carb foods. Plus, with the holiday season, staying with your eating plan can be challenging. Working with a dietitian or diabetes educator can be helpful, as can stocking more nutritious foods in your home. Drinking more water can also stave off hunger pangs and keep you from nibbling on unhealthy snack foods.

Not getting enough sleep or enough quality sleep can impact blood sugars, and even your blood pressure and your weight. Try to set up a regular sleep schedule. If you have problems with sleeping, let your provider know.

Finally, feeling stressed and anxious can lead to higher blood sugars. Counseling and medication may be part of your treatment plan, but don’t forget to devote time to doing things that you enjoy, getting outside, and spending time with family and friends.

Can SAD be prevented?

If you’ve had an episode of SAD, you may be able to keep it from coming back. Here’s what might work:

  • Using your light box regularly, before SAD symptoms occur
  • Staying active, doing at least 30 minutes of activity, at least three times weekly
  • Going outside every day
  • Eating healthy foods
  • Getting enough sleep
  • Finding ways to reduce stress

For more information on SAD, see this publication from the National Institute of Mental Health.

Want to learn more about managing stress? Read “Stress and Diabetes: Relaxation Techniques,” “Three Ways to Cope With Stress”  and  “Time to Focus on Emotional Health.”

Amy Campbell, MS, RD, LDN, CDCES

Amy Campbell, MS, RD, LDN, CDCES

Amy Campbell, MS, RD, LDN, CDCES on social media

A Registered Dietitian and Certified Diabetes Educator at Good Measures, LLC, where she is a CDE manager for a virtual diabetes program. Campbell is the author of Staying Healthy with Diabetes: Nutrition & Meal Planning, a co-author of 16 Myths of a Diabetic Diet, and has written for  publications including Diabetes Self-Management, Diabetes Spectrum, Clinical Diabetes, the Diabetes Research & Wellness Foundation’s newsletter,, and

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