Winter Light & Depression

During winter, the hours of sunlight decrease. Less sunlight has been shown to affect human mood, causing depression in some people. Those who suffer the winter blues are sensitive to the lack of light in winter. The hours of daylight start decreasing in September and reach their lowest in January. Winter depression, also called seasonal affective disorder, is more common in northern latitudes, such as the Arctic or Scandinavia, where there is less daylight during winter. According to The New York Times, people with Seasonal Affective Disorder feel lethargic and depressed in winter.

Seasonal Affective Disorder

• Seasonal affective disorder is also appropriately called S.A.D. People with normal mental health in the summer may become depressed as the hours of daylight dwindle during the onset of winter. According to the Mayo Clinic, people with S.A.D. start feeling symptoms in the fall and the depression continues into the winter when light levels are at their lowest. Symptoms include oversleeping, weight gain, carbohydrate cravings, fatigue, withdrawal from friends and family and, of course, depression.

Circadian Rhythm

• Your body has an internal clock, called the circadian rhythm, that lets you know when you should be asleep and awake. Sunlight maintains our circadian rhythms. With fewer hours of sunlight in the winter, circadian rhythms are disrupted, sometimes leading to depression. Your alarm clock is beeping loud and clear, but you want to roll over and go back to bed; your body wants to sleep because it's not dawn yet.

Melatonin Levels

• Melatonin is a hormone that affects sleep and mood. The increased hours of darkness of winter cause the body to produce more melatonin. We start producing melatonin at dusk, which signals sleep to the body. The production of melatonin usually peaks in the middle of the night during deep sleep. Healthy people stop producing melatonin at dawn. But if you suffer from winter depression, your body may be overproducing melatonin, which causes you to feel depressed and sleepy in winter.

Serotonin Levels

• Serotonin is a "feel good" chemical in the human brain, responsible for a sense of calm and well-being. The Mayo Clinic reports that the reduced hours of sunlight in the winter cause serotonin levels to drop. Humans have the lowest levels of serotonin in the winter. Serotonin levels can rise or drop based on the amount of sunlight on any particular day. Low levels of serotonin cause sadness, depression and, in extreme cases, can cause suicidal thoughts.

Treatment

• Light therapy, which involves spending a certain amount of time facing a special light box, increases serotonin levels and stops the overproduction of melatonin, especially if used in the morning. Antidepressants, such as Prozac, work to increase levels of serotonin in the body and treat seasonal affective disorder. Carbohydrates also raise serotonin levels, but choose good carbs over sweet and salty junk food. Dawn simulators create the feeling of waking up to sunlight, a good way to realign circadian rhythms.