Seasonal affective disorder (SAD) is a problem that affects people only at certain times of the year. Having symptoms at the same time every year is called “seasonality.” SAD tends to affect people most often during the winter months. The most common complaint related to SAD is depression.
People with depression may have trouble sleeping at night. They often have an excessive level of sleepiness during the day. They also tend to dream more quickly after falling asleep. These are other common symptoms of depression:
- Mood changes
- Ongoing feelings of sadness
- Loss of energy
- Isolation from other people
People with depression can have a hard time coping with struggles in their life. This can lead to a number of social problems.
Both SAD and depression tend to affect women more often than men. SAD also may be related to your body’s genes. Research has identified one gene as a genetic marker for SAD. People who have this gene are more likely to struggle with seasonal depression.
SAD is common during winter because there is much less sunlight than in the summer months. Light plays an important role as a visual timing cue for your body. Sunlight signals to your brain that it is time for your body to be awake and alert.
Your brain responds by adjusting your body temperature and certain hormone levels. In general, the dark months of winter throw off your body’s timing. As a result, you are more likely to be sleepy and sluggish during daytime hours.
The specific link between sunlight and SAD remains unknown. Some researchers think that SAD may be related to levels of serotonin and tryptophan in your body. Serotonin acts as a chemical messenger in the brain. It helps signal your body when it is time to sleep. Tryptophan is an amino acid that your body changes into serotonin.
Medications that increase serotonin levels have improved depressed moods in some people. One medication that has improved SAD symptoms is “nefazadone.” This drug is an antidepressant. It may be an effective medical treatment for people with SAD.
But the best treatment for SAD is increasing the amount of natural sunlight that you see during the day. Even if you can’t go outside, it may help if you spend more time sitting by a window. Yet you still may be unable to get enough sunlight during the short days of winter.
In this case, bright light therapy is an effective treatment option. This treatment exposes your eyes to intense but safe amounts of indirect light for a specific and regular length of time. This light is much stronger than standard indoor lighting. It is measured in units called “lux.”
A light box that you use for this therapy typically emits about 10,000 lux. This allows you to get enough light exposure in a short amount of time. A light that produces a lower level of lux requires a longer treatment session to get the same benefit.
You must contact a medical supply company to purchase one of these light boxes. You even have the option of buying a special “light visor.” It allows you to continue a treatment session even as you move around. Common side effects of light therapy include headaches and irritated eyes.
You should talk to your doctor if you have seasonal changes in your mood. He or she may prescribe an antidepressant for you. Ask your doctor if bright light therapy would be a better treatment option.
Never begin using bright light therapy without the supervision of a doctor. He or she will help you make sure that your treatment sessions are both safe and effective. Your doctor may refer you to a sleep specialist for more help.
By David A. Kristo, MD
Updated August 9, 2006