The symptoms of seasonal affective disorder (SAD) are cyclical. This means that symptoms tend to go away and then come back again at the same time each year. Symptoms usually begin in September and will normally start to ease by early spring. However, every individual experiences SAD differently and symptoms can vary from person to person.

At the start of the autumn, symptoms are usually relatively mild. As winter progresses and sunlight diminishes, symptoms tend to worsen.

SAD can be a difficult condition to live with and symptoms can have a significant impact on the way you live your day-to-day life.

The symptoms of SAD include:

• feeling tired and lacking in energy,
• sleep problems, such as disturbed sleep at night, sleeping for longer and feeling sleepy during the day,
• loss of sex drive,
• stress and anxiety,
• social withdrawal,
• feelings of guilt and worthlessness,
• weepiness,
• changes in appetite, such as a craving for carbohydrates and sweet foods,
• mood swings,
• weight gain,
• difficulty concentrating, and
• loss of interest in activities you used to enjoy.

For some people with SAD, when the symptoms start to ease in the spring, the depression-like feelings are replaced by a great burst of energy.

Therefore in spring you may experience:

• hyperactivity,
• persistently elevated mood,
• increased social activity, and
• unbridled enthusiasm.

These abnormally intense feelings of energy and enthusiasm are sometimes known as reverse SAD.

Summer SAD

In some rare cases, people experience their symptoms in the spring and summer months. The symptoms of summer SAD are different to that of the more common 'winter SAD'. They include:

• anxiety,
• insomnia,
• irritability,
• agitation,
• weight loss,
• poor appetite, and
• increased sex drive.

Winter blues

Up to eight in 10 people can experience feelings of lethargy, increased appetite and anxiety during the winter months. You may notice that you eat more, or put on weight during this time. These feelings are often known as winter blues or sub-syndromal SAD. The symptoms of winter blues are much milder than SAD and will not usually require any kind of treatment. Exercise is a good way to help boost energy levels if you are feeling lethargic during the winter period.