Some people experience a serious mood change when the seasons change. They may sleep too much, have little energy, and crave sweets and starchy foods. They may also feel depressed. Though symptoms can be severe, they usually clear up. This condition is seasonal affective disorder (SAD). It usually happens during the winter. A less common type of SAD happens in the summer.

What causes SAD? Some experts think it's a lack of sunlight during winter, when the days are shorter. In the United States, it is much more common in northern states. Light therapy, in which patients expose themselves to a special type of light for 30 minutes every day often helps. Other treatments include

• Medicines
• Changes in diet
• Learning to manage stress
• Going to a sunny climate during the cold months