As the leaves begin to fall from the trees, some of us begin to feel like hibernating. Sometimes called the winter blues, seasonal affective disorder (SAD) is a depression that strikes in late fall and continues until winter’s end. About a half million people in the United States report having the symptoms of seasonal affective disorder. But up to 20% of the U.S. population may suffer from a milder form of the winter blues. For people who suffer from SAD it’s a daily struggle to maintain their normal life.
Seasonal affective disorder is not fully understood, but it is predictable once diagnosed. It seems to affect women more than men. The first signs normally appear in young adults, although children and adolescents can also have SAD. It’s more common the farther north you travel from the equator. It’s also more common in higher altitudes and areas that are frequently cloudy or have overcast days. People who already have a mental challenge like attention deficit hyperactivity disorder, eating disorder, anxiety or panic disorder are also at greater risk for SAD.
There is a strong connection between the shorter days of fall and winter and SAD. The reduction in daylight hours appears to disrupt the body’s natural circadian rhythm. This is the 24-hour cycle that tells your body when to sleep and when to wake up. Different systems in the body are synchronized with an internal master clock in the brain. The clock is heavily influenced by factors in the environment, especially sunlight. That’s why shorter days and longer nights tend to disrupt the 24-hour cycle.
Sunlight is detected even when your eyes are closed. As the sun rises, your body gets the signal to start the wake up routine. A special set of cells in the retina of your eyes detects the sunlight. Those cells are connected to the hypothalamus which is responsible for triggering the release of hormones and regulating body temperature.
When there is less sunlight, your serotonin levels drop. Serotonin is a hormone that helps regulate your mood, supports feelings of well-being and helps you sleep. Exposure to the sun tells the hypothalamus to give you more serotonin which helps to alleviate the feeling of depression.
Another potential cause of SAD could be related to melatonin, a hormone that triggers sleep and causes drowsiness. When the sun goes down early, the hypothalamus signals that it needs melatonin so you can go to sleep more easily. But what if it’s only 5 o’clock in the evening? You certainly don’t want to go to sleep that early.
There is also some evidence that a deficit in vitamin D can make seasonal affective disorder worse because vitamin D promotes healthy serotonin levels. Since much of the body’s production of vitamin D is triggered by exposure to sunlight, we all experience a deficit of this nutrient in the shorter days of fall and winter.
If you’ve noticed any of the following, you may be experiencing seasonal affective disorder:
- Lack of energy
- A craving for carbs and overeating
- Loss of interest in those things you normally enjoy like social activities
- Sleeping a lot more than normal
- A shift in your mood that seems to come around the same time every year
If these symptoms seem familiar and significant, you may want to consult with your doctor or a mental health professional.