Seasonal Affective Disorder and Winter Blues: Symptoms, Causes and What Helps
How to tell the winter blues from seasonal affective disorder (SAD), why shorter days affect mood, sleep and energy, and the treatments and habits that help, including light therapy, morning light, movement, vitamin D and when to see a doctor.
Every year it sneaks up on you. The clocks change, it's dark by the time you leave work, and somewhere around November you notice you'd rather crawl under a blanket than do just about anything. You're sleeping more but still tired. You want carbs constantly. Things that usually make you happy feel a bit gray.
If that sounds familiar, you might be dealing with the winter blues, or something more serious called seasonal affective disorder, often shortened to SAD. Either way, you're not imagining it, and you're not just being lazy. Shorter days really do affect your brain and body, and there are proven ways to feel better.
What is seasonal affective disorder?
Seasonal affective disorder is a type of depression that follows a seasonal pattern. For most people it starts in late fall or early winter and lifts in spring and summer. Clinicians now often describe it as major depressive disorder with a seasonal pattern.
Less commonly, some people have the reverse, summer-pattern SAD, with symptoms that start in late spring or summer.
Winter blues vs. seasonal affective disorder
Lots of people feel a little lower, slower or more tired in winter. That's the winter blues, and it's very common. SAD is more intense and lasts longer.
| Winter blues | Seasonal affective disorder | |
|---|---|---|
| Mood | A bit low or flat | Persistent depression most of the day, nearly every day |
| Daily life | Mostly unaffected | Interferes with work, relationships or daily tasks |
| Duration | Comes and goes | Lasts weeks to months, returning most years |
| Enjoyment | Still enjoy most things | Loss of interest in things you used to love |
| Treatment | Self-care often helps | Often needs light therapy, talk therapy or medication |
If you're not sure which one you're dealing with, a doctor can help sort it out.
Symptoms of seasonal affective disorder
Winter-pattern SAD shares many symptoms with depression, plus a few that are particularly common in the darker months:
- Feeling sad, hopeless or empty most of the day
- Losing interest in activities you normally enjoy
- Low energy and feeling sluggish
- Sleeping much more than usual (oversleeping)
- Craving carbohydrates and gaining weight
- Trouble concentrating
- Withdrawing from friends and social plans, sometimes described as feeling like "hibernating"
- Feeling irritable or anxious
- Thoughts of death or suicide in more serious cases
Summer-pattern SAD more often involves trouble sleeping, poor appetite, weight loss, restlessness and anxiety.
What causes seasonal affective disorder?
Researchers don't fully understand SAD yet, but several factors seem to play a part.
Less sunlight. Shorter days and weaker sunlight in fall and winter can throw off your body's internal clock, known as your circadian rhythm. That can affect when you feel sleepy and alert, and your mood.
Serotonin changes. Serotonin is a brain chemical involved in mood. Reduced sunlight may affect serotonin activity in some people.
Melatonin shifts. Your body makes melatonin, a hormone that helps regulate sleep, in response to darkness. Longer nights can change melatonin patterns, which may contribute to sleepiness and low energy.
Vitamin D. Your skin makes vitamin D from sunlight. Lower levels in winter may be linked to mood in some people, though the research on vitamin D and SAD is mixed.
Who is most at risk?
SAD can affect anyone, but it's more common in:
- People who live farther from the equator, where winter days are much shorter
- Women, who are diagnosed more often than men
- Young adults
- People with a personal or family history of depression or bipolar disorder
Treatments that help seasonal affective disorder
Light therapy
Light therapy is one of the main treatments for winter-pattern SAD. It involves sitting near a special light box that gives off bright light, often 10,000 lux, for about 20 to 30 minutes each morning. The light box is placed at an angle a set distance from your face while you read, eat breakfast or work. You don't stare straight at it.
Many people notice improvement within a week or two. A few things to know:
- Choose a light box made for SAD that filters out UV light.
- Morning use usually works best.
- Side effects can include eye strain, headaches or feeling wired. Using it at night can disrupt sleep.
- People with bipolar disorder, certain eye conditions or who take medications that increase light sensitivity should talk to a doctor first.
Talk therapy
Cognitive behavioral therapy (CBT), including a version adapted specifically for SAD, can help you challenge negative thoughts and plan enjoyable, energizing activities during the darker months. Some research suggests the benefits of CBT may last into future winters.
Medication
Antidepressants, particularly certain SSRIs, may be prescribed for SAD. One antidepressant, bupropion, has been approved in an extended-release form to help prevent seasonal depressive episodes in people with a history of SAD. A doctor can talk through whether medication makes sense for you.
Vitamin D
If blood tests show you're low in vitamin D, a doctor may recommend a supplement. Vitamin D isn't a proven standalone treatment for SAD, but correcting a deficiency is good for overall health. Don't take high doses without guidance.
Daily habits that ease the winter blues
Whether you have SAD or just a seasonal slump, these habits can make winter feel a lot lighter.
Get outside in the morning
Even on cloudy days, outdoor light is much brighter than indoor lighting. A 10- to 20-minute walk in the morning can help set your body clock and lift your mood.
Bring more light indoors
Open curtains as soon as you wake up, sit near windows when you can and trim back anything blocking natural light. Our guide to a healthy home environment has more ideas for making your space feel brighter.
Keep moving
Exercise is a well-proven mood booster. You don't need intense workouts. Brisk walks, dance videos, a gym class or short exercise snacks throughout the day all count. Aim for 150 minutes a week if you can.
Keep a regular sleep schedule
It's tempting to sleep in when it's dark, but going to bed and waking up at the same time each day helps steady your circadian rhythm.
Eat for steady energy
Carb cravings are common in winter. Rather than fighting them completely, balance them with protein, fiber, vegetables and whole grains to avoid energy crashes.
Plan things to look forward to
Schedule small pleasures through the winter: a weekly movie night, a class, a trip to a museum, a dinner with friends. Our awe walks guide is a lovely way to find small moments of wonder, even in winter.
Stay connected
Seasonal low mood often makes people pull away. Make a plan to see or talk to at least one friend each week, even when you don't feel like it. Our guide to loneliness and health explains why this matters so much.
Start early
If you know winter tends to hit you hard, start your habits, like morning light and regular exercise, in early fall before symptoms set in.
When to see a doctor
See a doctor or mental health professional if:
- Your low mood lasts more than two weeks
- You're struggling to keep up with work, school or relationships
- You're sleeping much more or much less than usual
- You're using alcohol or food to cope
- You feel hopeless, or have thoughts of death or suicide
If you're in crisis, call or text 988 in the U.S. or contact local emergency services.
Winter wellness checklist
Print this out or save it to your phone for the darker months:
- Morning light within two hours of waking
- Movement most days, even 10 minutes
- One social plan a week
- Regular bedtime and wake time
- One thing to look forward to each week
- A check-in with yourself: how's my mood, honestly?
Frequently asked questions
What is the difference between the winter blues and SAD?
The winter blues are mild, common dips in mood or energy during colder months. SAD is a form of depression that's more intense, lasts weeks to months and interferes with daily life.
When does seasonal affective disorder start?
For most people, winter-pattern SAD starts in late fall or early winter and improves in spring. Some people have a summer pattern instead.
Does light therapy really work?
Light therapy is an established first-line treatment for winter-pattern SAD, and many people notice improvement within a couple of weeks of daily morning use.
Can vitamin D help with SAD?
Vitamin D may help if you're deficient, but research on vitamin D as a SAD treatment is mixed. Ask your doctor about testing before taking supplements.
Can I prevent seasonal affective disorder?
You can lower the impact by starting light therapy, outdoor time, exercise and good sleep habits in early fall, before symptoms usually begin. Talk to your doctor about a prevention plan if SAD returns every year.
Brighter days start with small steps. See how your emotional wellness fits into the full picture with our free wellness wheel quiz.
