December 18, 2023

The Science Behind Seasonal Affective Disorder and 3 Ways to Cope

photo of Perry Santanachote

Written By

Perry Santanachote

photo of Mary Stratos, PA-C, IFMCP

Medically Reviewed By

Mary Stratos, PA-C, IFMCP

Lifeforce Physician Assistant

photo of Leah Johansen, MD

Medically Reviewed By

Leah Johansen, MD

Lifeforce Physician

The Science Behind Seasonal Affective Disorder and 3 Ways to Cope

Your wardrobe might be ready for the fall-to-winter transition, but is your mind prepared for the darker days ahead? Along with falling leaves and fresh snow, this time of year can bring about seasonal affective disorder (SAD), a form of major depression that emerges primarily during the fall and winter months when temperatures drop and the days are shorter. 

“Human beings are seasonal organisms,” says Paul Desan, MD, PhD, director of the Winter Depression Research Clinic at the Yale School of Medicine. “Your body knows whether it’s summer or winter and the chemistry of the brain changes in reaction even though we live in settings with artificial illumination.”

If you feel depressed during the colder months, you’re not alone. Approximately 5% of U.S. adults experience SAD but at least 10% of the population has a milder case called subsyndromal SAD. 

“Those with subsyndromal SAD are not severely affected enough that we would diagnose them with an episode of clinical major depression,” says Dr. Desan. “But they don't feel the same vigor or have the same energy or their appetite goes up, and they want help with that.”

Going into this year’s winter, our experts have advice on how to spot SAD symptoms and what to do before the darkness sets in.

Understanding Seasonal Affective Disorder

Some experts believe the lack of morning light and changes in weather patterns disrupt the body’s circadian rhythm — the 24-hour biological clock that regulates how our bodies function throughout the day. 

Normally, the body produces melatonin at night to help promote sleep and levels taper off at dawn when you wake up. But if you have SAD, melatonin peaks later and lingers longer into the morning, which makes it harder to wake up and be alert throughout the day.

Reduced daylight may also disrupt serotonin, a hormone that helps regulate mood and feelings of well-being. In the winter, serotonin levels are at their lowest because sunlight boosts its production.

Seasonal Affective Disorder SymptomsSeasonal Affective Disorder Symptoms

Physical symptoms of SAD reveal themselves before ennui settles in, according to the Columbia University Irving Medical Center. That means you can nip depression in the bud before it takes root. These symptoms include:

  • Difficulty waking up on schedule and sleeping more

  • Daytime fatigue

  • Craving carbohydrates

  • Weight gain

Once the depression hits, usually weeks after the physical symptoms appear, the symptoms look like typical depression, including:

  • Loss of motivation and interest in work or other activities

  • Persistent feelings of hopelessness and sadness

  • Difficulty concentrating

  • Social withdrawal

  • Anxiety

The good news is that since the onset of SAD is predictable, countermeasures can begin before the mood swing is severe. 

Who Is Most Susceptible to Seasonal Affective Disorder?

Because these winter blues are connected to weather and daylight hours, those living in regions farther from the equator are more susceptible to its effects. Dr. Desan says people at the mid-Atlantic latitudes and above should worry about SAD but people who live further south are less afflicted.

Other groups at risk for developing SAD also include women of childbearing age — who are four times more likely to be diagnosed — young adults, and people who have previously experienced depression or bipolar disorder symptoms.

3 Ways to Treat Seasonal Affective Disorder3 Ways to Treat Seasonal Affective Disorder

Winter can be a bear, but you’re a human and hibernation isn’t an option. It is essential to be proactive and seek help as soon as possible. If left untreated, depression can lead to a host of other health problems.

“It is becoming more clear the relationship between mental health and chronic disease,” says Dr. Leah Johansen, MD, a Lifeforce Physician. “Whether seasonal or ongoing, depression can predispose to inflammatory conditions that manifest as endocrine, musculoskeletal, and cardiovascular disease.”

There are several options to help manage SAD, but if you are depressed for more than two weeks, talk to your doctor or other healthcare professional to identify the most beneficial treatment plan. In some cases, talk therapy or an antidepressant might be right for you. For milder depression, our experts have science-backed self-care tips that might be enough. 

1. Reset your biological clock with a bright light box. 

Light therapy boxes are widely considered a first-line treatment option for SAD, according to a review published in 2017. The home-based treatment emits bright artificial light in wavelengths that mimic sunshine to help regulate circadian rhythms and minimize the impact of shorter days. 

Not any light will do, and the proliferation of cheap and weak lights on the unregulated market can make shopping for one a challenge. To help, Dr. Desan’s clinic at Yale has vetted a number of models and lists recommendations on its website. Lights that give off 10,000 lux of cool white fluorescent or full-spectrum light are widely proven effective in clinical trials for SAD. It’s the equivalent of being outdoors at midday in July, says Dr. Desan.

Experts recommend using a light box for 30 minutes daily within the first hour after waking up, ideally before 8 a.m., but everyone is different. The Center for Environmental Therapeutics provides a free self-guided questionnaire created by Columbia researchers to help determine the most effective time of day for light therapy for you.

People typically notice an effect within a few days, says Dr. Desan, but may take a few weeks to feel the full effect of the light.

Note: You should not use light therapy if you take medicines that make you photosensitive, such as certain psoriasis drugs, antibiotics, or antipsychotics. If you have a retinol disease, check with your eye doctor before starting treatment.

2. Stay active and get outdoors. 

Exercise has been proven to reduce symptoms of depression and anxiety. “Get outside as much as possible,” says Dr. Johansen. “Aerobic exercise at moderate and vigorous intensities can have a significant benefit. Walking is great, as well as morning yoga.” Strength and resistance exercises three to four times a week can also combat depression. Make sure your sessions last 30 to 60 minutes.

Prioritize Nutrition and Lower Carb Intake3. Prioritize nutrition and cut down on carbs.

Studies have found that the change in seasons often leads to an increase in emotional eating and an overload of starchy and sugary foods. Your sister’s holiday cookie swap doesn’t help. Try to fight the urge as there are plenty of foods that affect your mood in a positive way. 

“Eat warming foods like ground chia or ground flax ‘noatmeal’ and drink warming herbal teas such as ginger and cinnamon to support your constitution,” says Dr. Johansen

Crack down on carb cravings by snacking on walnuts, which have been shown to significantly reduce appetite for these types of foods. And be mindful of alcohol use. “Alcohol can provide an initial boost of dopamine but the secondary side effects can cause more emotional depression and anxiety,” says Dr. Johansen. “Look for fun mocktail recipes if you know you need to cut back but are struggling to commit.”

And if you’re curious about turning to supplements like vitamin D to treat SAD, take note: While one controlled study involving healthcare professionals did not show vitamin D to have therapeutic benefits between SAD over placebo (if you already had vitamin D levels over 50 nmol/L), both groups individually showed significant improvements in depressive symptoms, suggesting dose and perception matter, says Dr. Johansen. Other studies also suggest vitamin D supplementation can help with general depression symptoms if supplementing vitamin D levels to above 50 nmol/L.

Ready to make your health a priority for the new year? The Lifeforce Membership gives you access to biomarker testing (including a full hormone panel) every three months, plus ongoing personalized advice from a Lifeforce clinician and health coach. Learn more here

If you think you may be experiencing seasonal affective disorder, it’s essential to reach out and get help. See your doctor, contact a therapist, or talk to a close friend. If you are having suicidal thoughts or actions, get help immediately. 

National Suicide Prevention Lifeline: 1-800-273-TALK (1-800-273-8255)

Crisis Text Line: text CONNECT to 741741

This article was medically reviewed by: 

  • Mary Stratos, PA-C, Institute for Functional Medicine Certified Practitioner

  • Leah Johansen, MD, Board Certified Family Practice Doctor, Institute for Functional Medicine Certified Practitioner

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