As a therapist living in the Northeast, I see an interesting phenomenon every time the calendar changes from summer to fall. Sometime around the end of October, requests for therapy start to skyrocket.

The weather, the seasons, and the length of day have a big impact on your mood. While some people experience a slight winter slump, others become downright depressed as the days get shorter.

Seasonal Affective Disorder (which has the fitting acronym SAD), often gets triggered shortly after daylight saving time begins. Going to work in the dark and coming home in the dark can take a serious toll on your mental health. Many people experience symptom progression as the months pass, until finally gaining relief again in the spring.

Scientists aren't exactly sure why people experience SAD. Some factors that may play a role include decreased serotonin and melatonin in the brain, stemming from the lack of sunlight. The decreased daylight disrupts your biological clock, which may also lead to sleep issues and mood problems.

Here are seven signs you may have SAD:

1. Irritability - Ironically, sometimes people with SAD don't look all that sad. Instead, they experience impatience and frustration.

2. Decreased energy - People with SAD often want to sit on the couch or stay in bed. They struggle to find the energy to carry out normal daily activities.

3. Weight gain - Although weight gain may result from the decreased activity that often accompanies the winter months, people with SAD tend to overeat. They usually reach for starchy and sweet foods which can contribute to weight gain.

4. Social problems - When SAD takes hold, many people don't want to socialize. They're often hypersensitive to criticism and their irritability can lead to relationship problems.

5. Sleep problems - Too much darkness can wreak havoc on a person's sleep/wake cycle. Many people with SAD have difficulty falling asleep and often, they don't feel rested in the mornings.

6. Increased anxiety - Sometimes, people with SAD experience increased anxiety and a decreased ability to tolerate stress.

7. Mood changes - Individuals with SAD experience a stark change in their mood and behavior during the winter, as compared to the summer months. An outgoing person may become withdrawn or an energetic person may become lethargic.

Treatment for SAD

You may be able to treat mild symptoms of SAD yourself. Bright sunlight-especially in the morning-and outdoor activity can help boost your mood. Going for a walk before work or during your lunch break may help alleviate some of the problem.

Find some enjoyable wintertime activities as well. Participating in outdoor activities-like snowshoeing or cross-country skiing-can reduce negative feelings about the winter months.

Bright light therapy is another effective option. A specially designed light box can simulate sunshine and regulate your body's internal clock. Similar to a bright spring day, daily exposure to the bright light may be able to prevent the body from producing too much Melatonin.

Cognitive behavior therapy and medication may also be effective in reducing symptoms. They may be used in combination, or they may be combined with bright light therapy.

If you think you may be experiencing SAD, talk to your doctor. Your physician can rule out physical health conditions and can suggest strategies that will make the winter months less gloomy.