Craving sunny summer days during gloomy winter months can sometimes result in sadness, loneliness and a lack of motivation. The shortage of sunshine limits how the brain handles our moods. 

For many people, this lack of sunlight is believed to be a main cause of seasonal affective disorder (SAD). Often beginning between the ages of 18 and 30, the American Psychiatric Association estimates that about 5 % of adults in the U.S. have SAD. 

SAD is a type of depression with seasonal patterns. Not to be confused with the “holiday blues,” the National Institute of Mental Health (NIH) explains that SAD is linked to shorter hours of daylight. Dates on the calendar, holiday gatherings and changes in work and school routines are not related to SAD. 

Forms and treatments 

There are two forms of SAD, winter-pattern and summer-pattern. Causes of summer-pattern SAD are less common but are related to trouble sleeping because of heat and more daylight.  

With winter-pattern SAD, the shortage of sunlight doesn’t create enough serotonin in our brains, resulting in low moods and tiredness. Harvard Health says instead, our brains create too much melatonin, the hormone that helps with our sleep-wake routine.  

If you are experiencing symptoms of SAD, you should first talk with a doctor. Treatments for winter-pattern SAD include counseling, medication and taking extra vitamin D. It may also be suggested that you try using light therapy boxes that model natural sunlight. 

How to use light therapy 

Ask your doctor to help you choose the best light box. The NIH suggests using a light with a 10,000-lux exposure (light intensity) for 30 to 45 minutes every morning from the fall to spring seasons. 

Mayo Clinic and Harvard Health offer tips for using a light box: 

Your doctor may suggest that you begin light therapy at the end of the summer to help get ahead of symptoms. Also, take advantage of rare sunny days throughout the fall and winter. Short walks can provide healthy doses of natural sunlight to boost your energy and mood.