Getting enough sunlight has shown to be effective for seasonal mood changes that happen in the darker winter months. Exposure to light in the morning helps the body's sleep/wake cycle work properly. Production of serotonin, a brain chemical that key in influencing our mood, is turned on in the morning upon exposure to light. During the winter when there is less sunlight, serotonin levels can drop, making us feel tired and prone to seasonal affective disorder (SAD).
One of the most simple ways to increase your exposure to light is to walk outdoors in the morning. Another option is to use special lights that simulate natural daylight. Studies have found they are effective. These lights can be found online. There are different types available, from light boxes to visors, that are typically used for 20-30 minutes a day. Look for lights with a minimum of 3,000 lux. many experts suggest 10,000 lux.