Article Highlights

  • SAD (seasonal affective disorder) is a more extreme form of the winter blues
  • Sunlight, or lack of it, plays a large role in SAD
  • Sunshine and Light Therapy can be used to regulate hormones and reduce SAD

Many of us dread the coming of winter, the darkness, the cold, the increased risk of getting the flu.

About 10 to 20 percent of the American population suffers from what is commonly referred to as the “winter blues.”

A smaller percentage, from about 4 to 6%, suffers from a more extreme form of the winter blues called Seasonal Affective Disorder or SAD.


SAD is a type of seasonal depression that shows up most of the time in late fall and lasts through the winter months, although there is a rare form that shows up in a smaller number of people in the late spring and lasts through the summer. In winter version of this disorder people suffer symptoms of depression including;

About 10 to 20 percent of the American population suffers from what is commonly referred to as the
“winter blues.”

• social withdrawal
• problems concentrating
• afternoon slumps with decreased energy and sleepiness during the day
• cravings for carbohydrates
• increased appetite and weight gain
• lack of energy and slow lethargic movements
• increased sleeping at night
• decreased interest in work and other activities

SAD is more common in higher latitudes, so the risk increases the more north you live. It is extremely rare in people who live within 30 degrees of the equator. Although the exact cause of SAD is unknown, most experts agree that sunlight, or the lack of it, plays a large role in the disorder.

SAD and Sunlight

Many of our body’s chemicals are regulated by sunlight, especially those that regulate mood and sleep. Because of the shorter days and the fact that people spend more time indoors, it is thought that these chemicals can become imbalanced during the winter months.

One theory is that reduced sunlight leads to a reduced production of serotonin in the brain. This neurotransmitter has a soothing, calming effect on the body. The result of low serotonin levels can be feelings of depression, fatigue, carbohydrate cravings (these foods tend to boost serotonin levels) and then, of course, weight gain.

For this reason, many SAD patients are treated with light therapy and usually have a good prognosis. Typically people treated with light therapy feel better in 2 to 4 days and their symptoms clear up in 2 to 4 weeks.

Light Therapy

Light therapy uses full spectrum light that closely mimic, the sun’s rays. This light is different than tanning beds because it does not contain UV rays. Small machines that can be used at home contain either a bright white light or light with a soft blue hue. Many of these machines have timers that can be programmed to gradually turn on before your alarm goes off making it easier for you to get out of bed and greet the day.

Light therapy has another benefit by reducing the hormone melatonin. Melatonin is manufactured by the body when it is dark to help us fall and stay asleep. Too much melatonin during the dark winter months may cause us to feel drowsy during the day. The combined effect of modifying the amount of melatonin in the nervous system and stimulating serotonin levels can help us feel better because of an antidepressant effect.

Everyone Can Use a Little Sunshine

The Stress Relief Center at Weber State University has a light machine that is used quite often during the entire year. These folks have not necessarily been diagnosed with seasonal depression. Many of them just don’t get enough natural light during the day or they just have a bit of the winter blues.

Director of the Stress Relief Center, Dr. Michael Olpin notes, “We have people who come in and just sit in front of it (the light therapy machine) for 20 to 30 minutes several times a week. They swear by it. They say they feel happier.” Light Therapy UnitsLight Therapy

How to Help

If you feel you aren’t getting enough natural light and can’t get to the Stress Relief Center, there are several models of light therapy machines that can be purchased for home use.

Light Therapy Units

We do not promote or recommend a specific model, and of course you need to make an educated decision when deciding if light therapy might be beneficial for you.

Another option you may want to consider is full spectrum light bulbs which can be placed in lamps and light fixtures throughout your home. Light BulbsFull Spectrum Bulbs

For more information on related topics read, “Why Bright Lights and Dark Nights are Essential for Sleep”