Yes. Seasonal depression, clinically called seasonal affective disorder (SAD), can happen in Southern California. Even in Santa Monica, winter days drop below 10 hours of daylight and the sun sets before 5 pm. That shift can disrupt sleep, energy and mood. Light exposure, routine, movement and therapy can all help.

Introduction

Every November, something strange happens to many people in Los Angeles. The weather is still lovely, the beach is right there, and yet they feel flat, tired and oddly heavy. Then comes the guilt: “How can I feel down when it’s 70 degrees outside?”

If that sounds familiar, you are not imagining it. Seasonal mood changes are not reserved for people in Minnesota or Seattle. Your body responds to light and darkness, not to how sunny your city looks in travel photos.

This guide explains what seasonal depression is, why it shows up in sunny places, how to tell the winter blues from something more serious, and which approaches have real research behind them.

What Is Seasonal Depression?

Seasonal affective disorder (SAD) is a type of depression that follows a recurring seasonal pattern, with symptoms that typically last about four to five months each year.

The National Institute of Mental Health (NIMH) describes two forms:

• Winter pattern SAD: Symptoms begin in late fall or early winter and ease in spring. This is the more common form.
• Summer pattern SAD: Symptoms appear in late spring or summer. It is less common but very real.

In clinical terms, SAD is not a separate diagnosis. It is major depression (or sometimes bipolar disorder) with a seasonal pattern. The word “seasonal” describes when it happens, not how serious it is.

Winter Blues vs. Seasonal Affective Disorder

Many people feel a little slower in winter. That’s normal. The difference is how much it affects your life.

Why Does Seasonal Depression Happen in Sunny Places?

Short answer: your internal clock reacts to day length, and Southern California still has short winter days.

Santa Monica sits at roughly 34 degrees north latitude. In late December, the area gets a little under 10 hours of daylight, compared with more than 14 hours in June. After daylight saving time ends on Sunday, November 1, 2026, sunsets jump back to around 5 pm and keep creeping earlier into December.

Here is what researchers believe happens in the body:

1. Circadian rhythm shifts. Less morning light can push your internal clock out of sync with your schedule.
2. Serotonin changes. Reduced sunlight is linked to lower activity of serotonin, a brain chemical tied to mood.
3. Melatonin overproduction. NIMH notes that people with winter pattern SAD may produce too much melatonin, the hormone that signals sleep, which can drive fatigue.
4. Vitamin D. Lower sunlight exposure can reduce vitamin D, which may play a role in serotonin activity.

The Hidden Factor: Indoor Lifestyles

Here’s something people in Los Angeles rarely consider. Sunny weather doesn’t help if you never see it. Many Westside professionals drive to work in the dark, sit in an office or home office all day, and drive home after sunset. A commute on the 10 or the 405 in December can mean almost zero natural light on weekdays.

In our experience, the people most surprised by seasonal depression are often the ones with the most indoor schedules.

What About “May Gray” and “June Gloom”?

Southern California has its own twist. The marine layer that blankets coastal areas like Santa Monica and Venice in late spring can bring weeks of overcast mornings. Some people notice their mood dips during this stretch too. It is not the classic winter pattern, but it shows how sensitive mood can be to light, even in mild climates.

What Are the Signs of Seasonal Depression?

The core signs are a persistent low mood plus changes in sleep, energy and appetite that return around the same time each year.

Common symptoms of winter pattern SAD

• Feeling sad, empty or hopeless most of the day
• Losing interest in activities you normally enjoy
• Oversleeping and still feeling tired
• Craving carbohydrates and gaining weight
• Pulling away from friends and social plans (some people call it “hibernating”)
• Trouble concentrating at work or school
• Feeling slowed down or heavy

Symptoms of summer pattern SAD

• Trouble sleeping
• Poor appetite and weight loss
• Restlessness, agitation or anxiety

Signs in children and teens

Young people often show seasonal mood changes differently. Watch for:

• Irritability instead of obvious sadness
• Grades slipping in late fall or winter
• Withdrawing from friends or activities
• Increased complaints of tiredness or headaches

If your child or teen shows these changes year after year, talk with their pediatrician or a child and adolescent therapist.

Who Is More Likely to Experience It?

Seasonal depression can affect anyone, but some factors raise the odds:

• A personal or family history of depression or bipolar disorder. SAD is more common in people with major depression or bipolar II disorder.
• Being a young adult. Onset often happens in young adulthood.
• Being female. Women are diagnosed more often than men.
• Living farther from the equator. Risk rises at higher latitudes, which is why moving from a sunnier place to a darker one can trigger symptoms. The reverse is also true. People who relocate to Los Angeles from cloudier cities sometimes expect their seasonal dips to vanish and are surprised when they don’t fully go away.
• Mostly indoor routines. Long office hours, night shifts and remote work can all limit daylight exposure.

What Actually Helps With Seasonal Depression?

The best supported approaches are light therapy, cognitive behavioral therapy (CBT), antidepressant medication and, in some cases, vitamin D, often combined with daily habits that protect your sleep and routine.

1. Light Therapy

Since the 1980s, light therapy has been a primary treatment for winter pattern SAD. According to NIMH, a typical approach involves sitting in front of a light box rated at 10,000 lux for about 30 to 45 minutes daily, usually first thing in the morning, from fall through spring.

A few practical points:

• Choose a box that filters out ultraviolet (UV) light.
• Consistency matters more than intensity. Using it at the same time each morning gives the best chance of results.
• Important caution: People with bipolar disorder, certain eye conditions, or those taking light sensitizing medications should only use light therapy with medical guidance. Bright light can trigger hypomania or mania in some people.

2. Talk Therapy, Especially CBT

Cognitive behavioral therapy adapted for SAD helps people identify negative thought patterns about winter (“The dark makes everything pointless”) and plan enjoyable, energizing activities to counter the urge to withdraw. NIMH reports that in research comparing the two, CBT and light therapy were similarly effective, and some evidence suggests CBT’s benefits may last longer in future winters.

Other approaches can help too. Attachment focused and psychodynamic therapy, for example, can explore why the season stirs up feelings of loneliness or loss, especially if winter holidays carry painful memories.

3. Medication

Some antidepressants, particularly selective serotonin reuptake inhibitors (SSRIs), are used to treat SAD. A psychiatrist or primary care doctor can assess whether medication makes sense for you.

4. Vitamin D

Research on vitamin D for SAD is mixed. Ask your doctor to check your levels before starting supplements rather than guessing.

5. Daily Habits That Make a Real Difference

These won’t replace treatment for clinical depression, but they genuinely help with milder symptoms:

• Get outside within an hour of waking. A 15 minute walk along Ocean Avenue or Palisades Park gives you far more light than indoor lamps.
• Move your workout outdoors. The beach path from Santa Monica to Venice is a perfect midday option.
• Work near a window. Even a simple desk shift can increase your daily light exposure.
• Keep a steady sleep schedule, including weekends.
• Plan social contact on purpose. Put coffee dates and phone calls on the calendar before winter starts, when your motivation is higher.
• Limit alcohol, which can deepen low mood and disrupt sleep.

Common Mistakes People Make

1. Dismissing it because of the weather. “But it’s sunny here” is the most common reason people in Southern California ignore their symptoms.
2. Waiting until January. Starting light exposure and routines in October or early November works better than playing catch up.
3. Buying the wrong light box. Small “mood lamps” are often far below 10,000 lux and may do little.
4. Treating it as purely physical. Light helps, but seasonal depression often carries emotional themes like loneliness, grief around the holidays, or work burnout that deserve attention too.
5. Confusing holiday stress with SAD. Holiday stress comes and goes with events. SAD follows the season and lingers well past New Year’s.

When Should You Talk to a Professional?

Consider reaching out if your symptoms last more than two weeks, affect your work or relationships, or return every year.

Seek help sooner if you notice:

• Feelings of hopelessness or worthlessness
• Using alcohol or other substances to cope
• Significant changes in eating or sleeping
• Your child or teen’s mood or grades consistently dropping each winter

If you are having thoughts of harming yourself, call or text 988 to reach the 988 Suicide and Crisis Lifeline, available 24 hours a day. In an emergency, call 911.

A licensed therapist can help you sort out whether you are dealing with seasonal depression, ongoing depression that worsens in winter, or something else entirely, such as burnout, grief or a life transition.

Key Takeaways

• Seasonal depression can happen in Southern California because day length, not temperature, drives the body’s seasonal response.
• Santa Monica gets a little under 10 hours of daylight in late December, and sunsets move to around 5 pm after daylight saving time ends.
• Winter pattern SAD often brings oversleeping, carb cravings, low energy and social withdrawal.
• Indoor routines and long commutes can cut light exposure dramatically, even in a sunny city.
• Light therapy and CBT both have strong research support, and CBT’s benefits may last into future winters.
• People with bipolar disorder should only use light therapy under medical guidance.
• Starting healthy routines in October or early November works better than waiting for symptoms to peak.

Frequently Asked Questions

Is seasonal depression real in Los Angeles?

Yes. Seasonal depression is linked to shorter days and less morning light, not cold weather. Los Angeles still loses more than four hours of daylight between June and December. Combined with indoor work schedules and long commutes, that change can trigger real symptoms in people who are sensitive to seasonal light shifts.

When does seasonal depression usually start?

Winter pattern seasonal depression usually begins in late fall or early winter and eases in spring. Many people notice the first changes in October or November, often around the end of daylight saving time, when evenings suddenly get dark earlier. Symptoms commonly last about four to five months.

How do I know if it’s SAD or just the winter blues?

The winter blues are mild and don’t stop you from functioning. Seasonal affective disorder involves a persistent low mood most days, plus changes in sleep, appetite and energy that interfere with work or relationships. If the pattern returns every year and lasts for months, it’s worth a professional evaluation.

Does daylight saving time make seasonal depression worse?

It can. When clocks fall back, evening light disappears suddenly, and many people leave work after dark. The abrupt shift can disrupt sleep and routines. Getting outside early in the day and keeping a consistent sleep schedule during the transition can soften the impact for many people.

How long should I use a light box each day?

According to NIMH, a common approach is about 30 to 45 minutes each morning in front of a 10,000 lux light box that filters UV light. Morning use is typical because it helps reset the body’s internal clock. Check with a doctor first, especially if you have bipolar disorder or eye conditions.

Can therapy help seasonal depression?

Yes. Cognitive behavioral therapy adapted for SAD has been shown in research to work about as well as light therapy, and its benefits may last longer in future winters. Therapy also helps address related issues like loneliness, holiday grief, work stress and patterns that make winter feel harder.

Can children and teens get seasonal depression?

Yes, though symptoms may look different. Children and teens often show irritability, falling grades, tiredness or withdrawal from friends rather than obvious sadness. If these changes appear around the same time each year, talk with your child’s pediatrician or a therapist who specializes in children and adolescents.

Does vitamin D help with seasonal depression?

Research on vitamin D for seasonal depression is mixed. Some people with low levels may benefit, while others see little change. The safest approach is to ask your doctor to test your vitamin D level before taking supplements, then follow their guidance on dose and timing.

Conclusion

Seasonal depression doesn’t care how sunny your zip code is. For many people in Santa Monica and across Los Angeles, shorter days, earlier sunsets and indoor routines are enough to shift sleep, energy and mood every fall. The good news is that seasonal depression is predictable, which means you can plan ahead. Morning light, steady routines, intentional social time and the right professional support can make the darker months feel much more manageable.

If winter tends to feel heavier than it should, you don’t have to push through it alone. Sally Hackman, PhD, MFT, has helped adults, couples, teens and children in Santa Monica for more than three decades, with sessions available in person or over Zoom. When you’re ready, you can reach out to arrange a consultation or call (747) 243-4897. Your first session is free if you decide not to continue.