SAD

Seasonal affective disorder (SAD) is a type of depression that's related to changes in seasons — SAD begins and ends at about the same times every year. If you're like most people with SAD, your symptoms start in the fall and continue into the winter months, sapping your energy and making you feel moody. Less often, SAD causes depression in the spring or early summer.
Treatment for SAD may include light therapy (phototherapy), psychotherapy and medications.
Don't brush off that yearly feeling as simply a case of the "winter blues" or a seasonal funk that you have to tough out on your own. Take steps to keep your mood and motivation steady throughout the year.

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.

Depression
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:

• Irritability
• Tiredness or low energy
• Problems getting along with other people
• Hypersensitivity to rejection
• Heavy, "leaden" feeling in the arms or legs
• Oversleeping
• 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:

• Depression
• Trouble sleeping (insomnia)
• Weight loss
• Poor appetite
• Agitation or anxiety

The specific cause of seasonal affective disorder remains unknown.

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​Treatment for seasonal affective disorder may include light therapy, medications and psychotherapy.

                      Focus on Light therapy

Light therapy is a way to treat seasonal affective disorder (SAD) and certain other conditions by exposure to artificial light. SAD is a type of depression that occurs at a certain time each year, usually in the fall or winter.
During light therapy, you sit or work near a device called a light therapy box. The box gives off bright light that mimics natural outdoor light.
Light therapy is thought to affect brain chemicals linked to mood and sleep, easing SAD symptoms. Using a light therapy box may also help with other types of depression, sleep disorders and other conditions. Light therapy is also known as bright light therapy or phototherapy.

​Why it's done
By Mayo Clinic Staff
You may want to try light therapy for a number of reasons:

• Your doctor recommends it for seasonal affective disorder or another condition.
• You want to try treatment that is safe and has few side effects.
• You want to increase the effectiveness of antidepressant medication or mental health counseling (psychotherapy).
• You need to avoid antidepressant medications during pregnancy or while breast-feeding.
• It may allow you to take a lower dose of antidepressant medication.

Conditions it's used forLight therapy is used as a treatment for several conditions, including:

• SAD
• Types of depression that don't occur seasonally
• Jet lag
• Sleep disorders
• Adjusting to a nighttime work schedule
• Dementia

Light therapy used to treat skin conditions such as psoriasis is different from the type of light therapy used for the conditions listed above. Light therapy for skin disorders uses a lamp that emits ultraviolet (UV) light. This type of light should be filtered out in light therapy boxes used for SAD and other conditions because it can damage your eyes and skin.

Follow up with your mental health team.