In most cases, seasonal affective disorder symptoms appear during late fall or early winter and go away during the sunnier days of spring and summer. However, some people with the opposite pattern have symptoms that begin in spring or summer. In either case, symptoms may start out mild and become more severe as the season progresses.
Seasonal affective disorder is a subtype of major depression that comes and goes based on seasons. So symptoms of major depression may be part of SAD, such as:
- Feeling depressed most of the day, nearly every day
- Feeling hopeless or worthless
- Having low energy
- Losing interest in activities you once enjoyed
- Having problems with sleeping
- Experiencing changes in your appetite or weight
- Feeling sluggish or agitated
- Having difficulty concentrating
- Having frequent thoughts of death or suicide
Fall and winter SAD
Symptoms specific to winter-onset SAD, sometimes called winter depression, may include:
- Tiredness or low energy
- Problems getting along with other people
- Hypersensitivity to rejection
- Heavy, "leaden" feeling in the arms or legs
- Appetite changes, especially a craving for foods high in carbohydrates
- Weight gain
Spring and summer SAD
Symptoms specific to summer-onset seasonal affective disorder, sometimes called summer depression, may include:
- Trouble sleeping (insomnia)
- Weight loss
- Poor appetite
- Agitation or anxiety
Seasonal changes in bipolar disorder
In some people with bipolar disorder, spring and summer can bring on symptoms of mania or a less intense form of mania (hypomania), and fall and winter can be a time of depression.
When to see a doctor
It's normal to have some days when you feel down. But if you feel down for days at a time and you can't get motivated to do activities you normally enjoy, see your doctor. This is especially important if your sleep patterns and appetite have changed or if you feel hopeless, think about suicide, or turn to alcohol for comfort or relaxation.
The specific cause of seasonal affective disorder remains unknown. Some factors that may come into play include:
- Your biological clock (circadian rhythm). The reduced level of sunlight in fall and winter may cause winter-onset SAD. This decrease in sunlight may disrupt your body's internal clock and lead to feelings of depression.
- Serotonin levels. A drop in serotonin, a brain chemical (neurotransmitter) that affects mood, might play a role in SAD. Reduced sunlight can cause a drop in serotonin that may trigger depression.
- Melatonin levels. The change in season can disrupt the balance of the body's level of melatonin, which plays a role in sleep patterns and mood.
Factors that may increase your risk of seasonal affective disorder include:
- Being female. SAD is diagnosed more often in women than in men, but men may have more-severe symptoms.
- Age. Young people have a higher risk of winter SAD, and winter SAD is less likely to occur in older adults.
- Family history. People with SAD may be more likely to have blood relatives with SAD or another form of depression.
- Having clinical depression or bipolar disorder. Symptoms of depression may worsen seasonally if you have one of these conditions.
- Living far from the equator. SAD appears to be more common among people who live far north or south of the equator. This may be due to decreased sunlight during the winter and longer days during the summer months.
Take signs and symptoms of seasonal affective disorder seriously. As with other types of depression, SAD can get worse and lead to problems if it's not treated. These can include:
- Suicidal thoughts or behavior
- Social withdrawal
- School or work problems
- Substance abuse
Treatment can help prevent complications, especially if SAD is diagnosed and treated before symptoms get bad.
There's no known way to prevent the development of seasonal affective disorder. However, if you take steps early on to manage symptoms, you may be able to prevent them from getting worse over time.
Some people find it helpful to begin treatment before symptoms would normally start in the fall or winter, and then continue treatment past the time symptoms would normally go away. Other people need continuous treatment to prevent symptoms from returning.
If you can get control of your symptoms before they get worse, you may be able to head off serious changes in mood, appetite and energy levels.