Seasonal Affective Disorder: When the Change of Seasons Changes Your Mood
As summer ends and the days become shorter, many people notice subtle changes in themselves. They may have less energy, want to sleep longer, spend more time at home, exercise less, or find it harder to get motivated. For some people, however, the change is much more significant. Depression begins to emerge at approximately the same time each year and improves when the seasons change again.
This condition is known as Seasonal Affective Disorder (SAD), commonly referred to as seasonal depression.
SAD is more than simply disliking winter or feeling disappointed that summer is over. It is a form of depression that follows a recurring seasonal pattern. Most commonly, symptoms begin during the fall or early winter and improve during the spring and summer. A less common form occurs during the spring or summer months.
How Common Is Seasonal Affective Disorder?
Estimates vary depending upon how strictly SAD is defined and studied. Research using formal diagnostic criteria has estimated that approximately 0.5% to 2.4% of the U.S. population experiences SAD, while other estimates have placed the number experiencing clinically significant seasonal affective disorder in a given year at approximately 5% of Americans.
SAD also tends to be more common among people living farther from the equator, where there are greater seasonal differences in the amount of daylight.
Regardless of the exact percentage, seasonal depression affects millions of Americans and can significantly interfere with work, relationships, motivation, and quality of life.
What Does Seasonal Affective Disorder Feel Like?
Winter-pattern SAD can include many of the same symptoms seen in other forms of depression, including:
Persistent sadness or depressed mood
Loss of interest in activities that were previously enjoyable
Fatigue and decreased energy
Difficulty concentrating
Decreased motivation
Social withdrawal
Feelings of hopelessness, worthlessness, or guilt
Sleeping more than usual
Increased appetite
Cravings for carbohydrates
Weight gain
For some people, the change happens gradually. They may initially think they are simply tired because of the colder weather or shorter days. Over time, however, they may realize that they are functioning differently from the way they do during the spring and summer.
An important clue is repetition: the symptoms tend to appear during a particular season and improve when that season ends.
Why Does Less Daylight Matter?
Researchers do not believe that SAD has one single cause. One of the leading explanations involves the relationship between sunlight and the body's internal biological clock, or circadian rhythm.
Our brains use light as an important signal for regulating sleep, wakefulness, hormones, energy, and mood. During fall and winter, people receive considerably less natural light, particularly in northern areas of the country.
Reduced sunlight may disrupt circadian rhythms and affect serotonin, a neurotransmitter involved in mood regulation. Seasonal changes can also affect melatonin, a hormone that plays an important role in sleep.
This helps explain why people with winter-pattern SAD often experience changes in both mood and sleep.
Can Lighting at Home Make a Difference?
Yes. Increasing exposure to light can be an important part of managing winter-pattern SAD.
Something as simple as opening blinds and curtains during the day, sitting near windows, and spending time outdoors during daylight hours may be helpful. Outdoor light can be considerably brighter than ordinary indoor lighting, even on cloudy winter days.
For people with more significant symptoms, bright-light therapy, sometimes called phototherapy, is an established treatment for winter-pattern SAD.
A therapeutic light box is much brighter than normal household lighting. A commonly recommended device provides approximately 10,000 lux of light while filtering out potentially harmful ultraviolet (UV) radiation.
Light therapy is generally used shortly after waking in the morning. Depending upon the device and the individual's treatment plan, a person might sit near the light for approximately 20 to 45 minutes each morning.
The person does not stare directly into the light. Instead, the light reaches the eyes indirectly while the person might eat breakfast, read, work, or drink coffee.
However, an effective alternative may be keeping the room well lit; you may consider using a 300 watt bulb in a floor lamp (just be sure the lamp is designed to safely handle a 300 watt bulb).
People considering light therapy should discuss it with a healthcare professional, particularly if they have an eye condition, take medication that increases sensitivity to light, or have bipolar disorder.
What About Temperature?
Winter brings two major environmental changes at the same time: less daylight and colder temperatures. It is easy to assume that cold weather causes seasonal depression, but the relationship is more complicated.
Reduced daylight appears to have a much clearer biological relationship with winter-pattern SAD than temperature itself.
Temperature can nevertheless affect mood and behavior indirectly.
When it becomes cold, people may spend considerably more time indoors. They may walk less, exercise less, cancel activities, see friends less frequently, and receive less exposure to natural daylight. Cold weather can therefore contribute to a lifestyle that reinforces isolation and inactivity.
There is also a less common summer-pattern SAD. People with summer-pattern SAD may experience insomnia, reduced appetite, weight loss, anxiety, agitation, or irritability. Heat may be relevant for some people with this form of seasonal depression, although the relationship between temperature and SAD is not as well established as the relationship between light and winter-pattern SAD.
Rather than thinking of temperature as the primary cause, it may be more useful to consider how seasonal changes in weather alter our routines, activity levels, sleep, social interaction, and exposure to daylight.
Antidepressant Medication
Antidepressant medications can be effective in treating SAD, particularly when symptoms are moderate or severe.
Selective serotonin reuptake inhibitors (SSRIs), which are commonly prescribed for depression, may be used for SAD as well. Bupropion extended-release is another antidepressant that has been specifically studied for preventing recurrent seasonal depressive episodes.
For someone who has experienced SAD repeatedly, a prescriber may recommend beginning medication before symptoms typically appear rather than waiting until depression becomes severe.
Antidepressants generally do not work immediately. It may take several weeks to experience their full benefit, and medication decisions should be made with a physician, psychiatrist, psychiatric nurse practitioner, or other qualified prescriber.
Talk Therapy Can Help
Psychotherapy can also be an effective treatment for seasonal depression.
Cognitive Behavioral Therapy adapted specifically for seasonal depression, sometimes called CBT-SAD, has been studied extensively. It can help people recognize depressive thinking patterns, reduce avoidance, remain engaged in meaningful activities, and develop strategies for coping with the difficult months.
But therapy can involve more than simply changing negative thoughts.
From a psychodynamic perspective, seasonal depression can also be explored within the larger context of a person's emotional life. Depression may interact with loneliness, relationship difficulties, unresolved losses, self-criticism, feelings about aging, family experiences, or longstanding patterns of withdrawing when distressed.
Understanding what happens internally when someone's mood declines can help the person respond differently rather than automatically retreating from life.
Psychotherapy can therefore address both the immediate symptoms of seasonal depression and the emotional patterns that may intensify those symptoms.
Sleep Matters
Sleep and SAD are closely connected.
People experiencing winter-pattern SAD often want to sleep longer, have difficulty getting out of bed, or feel tired despite spending more time asleep.
It may be tempting to respond to winter fatigue by sleeping late whenever possible or taking long naps. Unfortunately, an increasingly irregular sleep schedule can further disrupt the body's circadian rhythm.
Helpful habits can include:
Going to bed and getting up at approximately the same time every day
Getting bright natural or therapeutic light soon after waking
Avoiding excessive daytime sleeping
Limiting late-night screen use
Maintaining regular daytime activity
Creating a consistent bedtime routine
The goal is not simply to get more sleep. It is to get sufficient, restorative sleep while maintaining a stable sleep-wake rhythm.
Diet and Seasonal Depression
Winter-pattern SAD is often associated with increased appetite and cravings for carbohydrate-rich foods.
There is no special "SAD diet" proven to cure seasonal depression. However, eating patterns can influence energy, sleep, weight, and overall wellbeing.
Regular meals that include vegetables and fruits, whole grains, protein, and other nutrient-dense foods can help maintain more consistent energy throughout the day.
Comfort foods do not need to be eliminated. The goal is balance rather than restriction.
Alcohol deserves particular attention. Some people begin drinking more when they are depressed, lonely, bored, or spending more time at home. Although alcohol may temporarily create relaxation, it can interfere with sleep and worsen depressive symptoms.
Vitamin D has also received considerable attention because our bodies produce vitamin D in response to sunlight. Some people have low vitamin D levels during winter. Research on vitamin D as a specific treatment for SAD has produced mixed results, however, so supplements should not be viewed as a replacement for established depression treatments. A healthcare provider can determine whether testing or supplementation is appropriate.
Exercise and Getting Outside
When depression says, "Stay home," one of the most helpful responses may sometimes be to do the opposite.
Regular physical activity can support mood and reduce stress. Outdoor exercise has an additional advantage during winter because it combines physical activity with exposure to natural daylight.
This does not require an elaborate exercise program. Walking outside, particularly during daylight hours, can provide movement, environmental stimulation, and light exposure simultaneously.
The difficulty, of course, is that depression decreases motivation precisely when activity may be most beneficial. Rather than waiting until you feel like doing something, it can help to schedule activities in advance.
Sometimes action has to come before motivation.
Don't Let Winter Become a Season of Isolation
Social withdrawal is both a symptom of depression and something that can perpetuate it.
Winter makes isolation particularly easy. Darkness comes earlier, the weather may discourage going out, and staying home can gradually become the default.
Maintaining regular contact with other people can therefore be an important part of managing seasonal depression. Schedule dinner with a friend. Attend a class. Go to the gym. Visit family. Join a group. Make plans before the week begins.
For someone experiencing SAD, these activities are not merely ways of "keeping busy." They can be part of maintaining emotional health.
Preparing Before Winter Arrives
One advantage of SAD is that it can sometimes be anticipated.
If you recognize that your mood predictably begins declining every October, November, or December, you do not necessarily have to wait until you are depressed to respond.
Before symptoms become significant, consider establishing a regular sleep schedule, increasing morning light exposure, maintaining exercise, scheduling social activities, and speaking with your therapist or medical provider about a seasonal treatment plan.
For people with recurrent SAD, prevention can become part of treatment.
Seasonal Depression Is Still Depression
It can be easy to minimize seasonal depression because you know spring will eventually arrive. But several months is a long time to feel depressed.
You do not have to simply endure winter until the days become longer.
Seasonal Affective Disorder is a recognized and treatable form of depression. Depending upon the individual, treatment may include light therapy, antidepressant medication, psychotherapy, regular sleep, exercise, increased exposure to natural daylight, healthy eating, social connection, or a combination of these approaches.
Most importantly, recognizing a seasonal pattern provides an opportunity to do something about it.
If you notice that your mood, motivation, sleep, or energy repeatedly changes with the seasons, psychotherapy can help you better understand the pattern, address the emotional factors that may be contributing to it, and develop strategies for navigating the more difficult months of the year.