Seasonal depression (seasonal affective disorder): what it is, causes, treatment

The days start to shorten, darkness falls earlier in the day and — like clockwork — your mood dips. You feel tired, low energy, and sometimes just plain sad. For many people, shorter days and less daylight bring a change in mood. For some, this shift in mood can be more dramatic. When seasonal mood changes are significant, it’s known as seasonal depression or seasonal affective disorder (SAD). 

You can’t make the sun stay up longer, but there are many ways to treat the symptoms of seasonal depression, including exercise, light therapy, medications, cognitive behavioral therapy, and more. 

Here, learn more about what causes seasonal mood changes and what you can do to manage your symptoms — especially with exercises from our Hinge Health physical therapists.

What is seasonal depression?

Seasonal affective disorder, or SAD, is a type of depression that often occurs in the fall and winter. Less commonly, some people experience SAD during the spring or summer. Symptoms of SAD can vary, but common signs include:

• Feeling “down,” hopeless, or worthless

• Fatigue, low energy, and sluggishness

• Lack of motivation and interest in your usual activities

• Difficulty concentrating

• Sleep problems, including oversleeping

• Overeating and weight gain

• Social withdrawal

For most people, SAD symptoms improve when the days grow longer in the spring and summer months. 

The prevalence of SAD varies, but it may affect as many as one in five adults. It’s more common in young adults and women, people with a history of depression or bipolar disorder, and those with a family history of SAD. It’s also more common in people who live farther north, where winter daylight hours are more limited.

What causes seasonal depression?

Seasonal affective disorder is not yet fully understood, but experts believe it might be due to:

• Light-related changes in your brain chemistry. Sunlight plays a crucial role in the production of serotonin, a brain chemical that affects mood. When daylight hours decrease, serotonin levels can drop for people with SAD. 

• Increased melatonin production. People with SAD may produce too much melatonin, a hormone that regulates your sleep-wake cycle. This disruption can lead to SAD-related sleepiness.

• Vitamin D deficiency. Vitamin D is an important nutrient that contributes to bone health, immune function, and many other vital body functions. It’s also thought to play a role in mood by regulating the production of serotonin. Less sunlight during the winter months can cause vitamin D deficiency, which may contribute to SAD symptoms.

• Disruption of circadian rhythm (biological clock). The circadian rhythm is your body’s natural internal clock that affects physical, mental, and behavioral changes over a 24-hour period, mainly influenced by light and darkness. Your circadian rhythm helps regulate when you feel awake or sleepy.

How is SAD diagnosed?

Your healthcare provider may use a questionnaire to see if your symptoms match those of SAD. People with SAD typically have seasonal depression symptoms that occur:

• During the winter (or, less commonly, during the summer)

• During the same season for at least two years in a row (though not everyone with SAD has symptoms every year)

• More often during that specific season than at other times of the year

How exercise can help seasonal depression

Exercise is a powerful self-care tool that can be as effective as medication for mild to moderate depression, including seasonal depression. It’s accessible, low-cost, and practical for most people, offering benefits for both physical and mental health.

Here’s how exercise helps with seasonal depression symptoms: 

• Boosts brain chemicals. Exercise helps regulate the production of serotonin, dopamine, melatonin, and endorphins. These chemicals play a crucial role in mood regulation and can help reduce feelings of sadness and hopelessness. 

• Resets your biological clock. Regular physical activity can help reset your circadian rhythm, leading to better sleep and reduced fatigue.

• Improves sleep and reduces anxiety. Exercise can improve sleep quality, reduce anxiety, and boost energy levels, all of which help manage SAD symptoms.

• Helps you stay social. Participating in group exercises or working out with friends can combat feelings of isolation and give you a sense of community and support.

• Reduces stress. Exercise is a natural stress reliever, which can help you fall and stay asleep more easily.

• Regulates body temperature.The drop in body temperature after exercise can make you feel sleepy and help you fall asleep more easily.

• Improves self-esteem and motivation. Accomplishing exercise goals, even small ones, can promote a sense of achievement, which can boost motivation and mood.

Best exercise for seasonal depression

Regular physical activity can significantly help manage symptoms of SAD. Aim for 20–60 minutes of exercise most days, but even short “movement snacks” can be beneficial. Consistency is key. Here are some of the best types of exercise for SAD:

• Aerobic activities. Walking, running, swimming, biking, and dancing are excellent choices. Rhythmic, continuous movements can be particularly effective in boosting mood.

• Resistance training. Bodyweight exercises, resistance bands, or weightlifting can help you feel stronger and more capable, which can boost your self-worth and confidence.

• Mind-body exercises. Yoga, tai chi, and stretching can provide both physical and emotional benefits, helping you feel more centered and calm.

Always check with your provider before starting a new exercise program.

More ways to treat seasonal depression

Other effective treatments for SAD include:

Light therapy

Light therapy, or phototherapy, is effective for people with fall and winter SAD. It involves regular exposure to very bright light, which may work by increasing serotonin levels, shutting down melatonin production, and helping regulate your circadian rhythms. 

You can buy a phototherapy light box at pharmacies or online. Light boxes are not FDA tested or approved, so ask your provider for a quality light box recommendation. Most people use phototherapy for 20 to 30 minutes in the morning, but you should consult your provider for specific recommendations. 

If you have certain eye diseases or are taking medications that make you sensitive to sunlight, light therapy might not be a good choice for you. 

Medications

Antidepressant medications like selective serotonin reuptake inhibitor (SSRI) drugs can increase serotonin levels and help address your SAD symptoms. Talk to your doctor to see if these medications might be helpful for you.

Vitamin D supplementation. Your body makes vitamin D when your skin is exposed to sunlight. Since there’s less sunlight in winter, people with SAD might have lower vitamin D levels, which can reduce serotonin. People with seasonal depression might benefit from vitamin D supplements, particularly in regions with limited sunlight exposure during colder months. Your provider can check your vitamin D levels.

Mental health support

Therapy, especially cognitive behavioral therapy (CBT), can help manage symptoms of seasonal depression by helping you identify and change negative thought patterns and behaviors to improve your mood and overall well-being. CBT is effective for SAD and can be as good as light therapy with longer-lasting benefits, though it might take longer to see results.

Tips for staying active in winter

Staying active in the winter can be challenging, but with a few adjustments, you can keep your exercise routine on track. Here are some tips to help you stay motivated and engaged during the colder months.

• Adjust routines for daylight hours and weather. Plan activities during daylight hours, such as lunchtime walks.

• Embrace winter activities like skiing, snowshoeing, or even a brisk walk in the park (bundled up, of course).

• Set manageable goals. Start small and gradually increase the intensity and duration. Choose activities you enjoy and can stick with. 

• Consider group classes or workout partners. Joining a class or finding a workout buddy can provide motivation and accountability. Virtual communities can also be a great resource.

Other lifestyle tips for managing seasonal affective disorder

In addition to exercise and other treatments, there are many lifestyle tips and self-care strategies that can help you manage seasonal depression symptoms:

• Good sleep hygiene. Getting enough sleep is crucial for managing SAD. Try to go to bed and wake up at the same time every day, even on weekends. This helps keep your body’s internal clock in check and improves the quality of your sleep. Make your bedroom a peaceful place by keeping it cool, dark, and quiet. Use earplugs, blackout curtains, or a white noise machine to block out any distractions. Reserve your bedroom for sleep and intimacy only — avoid activities like scrolling on your phone or watching TV in bed.

• Nutrition. Eating a healthy, balanced diet can improve your mood and energy levels. Focus on foods rich in omega-3 fatty acids and complex carbohydrates. Omega-3 fatty acids, found in fish like salmon and flaxseeds, may boost your mood. Complex carbohydrates, found in whole grains and vegetables, can give you more energy. 

• Stay hydrated. Dehydration can worsen fatigue. Avoid excessive caffeine and alcohol, which can negatively affect mood and sleep.

• Mindfulness and stress reduction techniques. Practicing mindfulness and stress reduction techniques can help you manage stress and cope better with seasonal depression symptoms. Techniques like deep breathing and relaxation exercises help you focus on the present moment, relax both your mind and body, and feel more in control.

When to seek professional help

If your SAD symptoms are severe, persistent, or significantly affect your daily life, it’s important to consult a healthcare professional. While exercise and self-care can be highly effective, they don’t always replace medical or psychological treatments. Your healthcare provider can help you develop a comprehensive plan to manage your symptoms.

In rare cases, some people with SAD may experience suicidal thoughts or behavior. If you or someone you know is experiencing these extreme symptoms, contact the National Suicide Prevention Hotline at 988. This is a 24/7 free, confidential service available to people in crisis. Visit https://988lifeline.org for more suicide prevention resources.

How Hinge Health can help you

If you have joint or muscle pain that makes it hard to move, you can get the relief you’ve been looking for with Hinge Health’s online exercise therapy program.

The best part: You don’t have to leave your home because our program is digital. That means you can easily get the care you need through our app when and where it works for you.

Through our program, you’ll have access to therapeutic exercises and stretches for your condition. Additionally, you’ll have a personal care team to guide, support, and tailor our program to you.

See if you qualify for Hinge Health and confirm free coverage through your employer or benefit plan here.

This article and its contents are provided for educational and informational purposes only and do not constitute medical advice or professional services specific to you or your medical condition.

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