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), medications and psychotherapy.

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. Less commonly, 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.

Signs and symptoms of SAD may include:

• Feeling depressed most of the day, nearly every day
• Losing interest in activities you once enjoyed
• Having low energy
• Having problems with sleeping
• Experiencing changes in your appetite or weight
• Feeling sluggish or agitated
• Having difficulty concentrating
• Feeling hopeless, worthless or guilty
• Having frequent thoughts of death or suicide

Fall and winter SAD

Symptoms specific to winter-onset SAD, sometimes called winter depression, may include:

• Oversleeping
• Appetite changes, especially a craving for foods high in carbohydrates
• Weight gain
• Tiredness or low energy

Spring and summer SAD

Symptoms specific to summer-onset seasonal affective disorder, sometimes called summer depression, may include:

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