It’s the post-holiday slump, and there seems to be no end in sight to the dreary, cold weather. If your child seems a bit blue lately, it could be a mild case of seasonal affective disorder (SAD).

SAD is a type of depression that occurs as daylight hours become shorter. Affecting up to 20% of adults each winter, SAD affects kids, too. The limited studies of children with SAD find that teenagers and females living in northern climates are among those most affected. Symptoms, which can last a couple of months, include depression, irritability, difficulty concentrating on schoolwork and craving carbohydrate-rich foods, according to the American Academy of Pediatrics (AAP).

Studies have linked SAD to changes in the circadian rhythm — the body’s natural sleep and waking cycle. During winter, the body starts making more melatonin, the hormone that encourages sleep. It also makes less serotonin, the hormone that fights off depression. People who live north of the equator get less sunlight and spend more time indoors, adding to the problem.

Recent research has shown that bright white fluorescent lights can be used to treat SAD with few to no side effects in adult patients. However, evidence-based studies are not yet available on light therapy in children. For those considering trying light therapy at home, the National Alliance on Mental Illness advises purchasing an artificial light therapy box with an ultraviolet filter that is labeled as giving off 2,500 to 10,000 lux. The box should be placed at eye level and used in the morning for 20 to 60 minutes throughout the season, even after symptoms disappear.

To help children avoid mild cases of the winter blues, the AAP offers the following tips:

  • Get outdoors every day, even on cloudy days.

  • Eat a healthy diet that is full of fruits, vegetables and whole grains.

  • Keep active. Exercise has been proven to boost mood in children.

Parents should contact their pediatrician if the child’s mood does not improve or worsens.

© 2012 American Academy of Pediatrics. This Parent Plus may be freely copied and distributed with proper attribution.