Does Winter Make You Depressed?
As the season transitions from autumn to winter, the waning daylight can trigger seasonal affective disorder (SAD). It’s different than just feeling sluggish about going out because it’s cold and grey. SAD is a type of depression distinguished by its seasonality. Symptoms include sluggishness, sadness, and losing interest in previously enjoyed activities. These symptoms are not occasional; rather, they persist throughout the season.
“For most people with SAD, symptoms start in the fall and continue into the winter months, sapping your energy and making you feel moody,” explains geriatric medicine specialist Michelle Eslami, MD, UCLA Medical Center. “Less often, SAD causes depression in the spring or early summer.”
People living in the northern parts of the United States are more at risk for SAD, than those living in southern states. In Florida for example, only about 1 percent of the population is likely to have SAD whereas about 10 percent of people living in Alaska or New England may be affected. Women are four times more likely to be diagnosed with SAD than men. Those who have depression or a family history of it are also more likely to suffer from SAD. While older people can have SAD, younger adults are more at risk.
WHAT YOU SHOULD KNOW
To be diagnosed with SAD, people must meet the full criteria for major depression coinciding with specific seasons, for at least two years. Symptoms include:
➢ Having low energy
➢ Excessive sleepiness
➢ Craving for carbohydrates
➢ Social withdrawal (feel like “hibernating”)
What Light Has to Do With It
The lack of daylight can disrupt the body’s natural sleep/wake clock, known as the circadian rhythm. This internal rhythm is controlled by brain cells that react to light and dark. The brain cells receive signals by way of the eye’s optic nerve. When light is sensed, cells tell the internal clock it’s time to be awake. The light also triggers other parts of the brain that affect hormones and body temperature, which play a role in feeling sleepy or awake.
Light suppresses melatonin, but darkness signals its release. Melatonin, a hormone, naturally helps usher in sleep as night begins. Because it gets darker earlier in the winter, that may trigger people with SAD to overproduce melatonin. Too much melatonin may be why people with SAD sleep more and lack energy.
Less sunlight can lead to lower levels of vitamin D. The vitamin is thought to play a role in serotonin activity. Serotonin, a neurotransmitter, is a chemical that helps move information from one part of the brain to another. It influences a wide variety of brain and body functions, including mood and social interactions.
Seasonal Serotonin Changes
A small study from the University of Copenhagen found that people with SAD showed seasonal differences in the way they regulate the serotonin compared to those without the disorder. Researchers scanned 11 SAD patients and 23 healthy individuals using positron emission tomography (PET) scans. They found summer-to-winter differences in the levels of the serotonin transporter (SERT) protein. SERT decreases serotonin in the brain. Low levels of serotonin are linked to depression. SAD patients showed higher levels of SERT in the winter months, corresponding to a greater removal of serotonin from the brain in winter.
Beyond Light: CBT Lasts Longer
Light therapy has been the primary treatment for SAD since the 1980s. To be effective, daily use is required. The general recommendation is to sit in front of a lightbox first thing in morning for at least 30 minutes. While light therapy has shown to improve SAD symptoms, the challenge for many people has been adhering to the daily regime.
According to a recent study published in the American Journal of Psychiatry, a longer-term fix for SAD may be cognitive behavioral therapy (CBT).
“It appears that CBT, a type of talk therapy, had a better long-term effect than light therapy, with less return of symptoms,” says Dr. Eslami. “The therapy gave patients practical tools to continue with beyond the office visit, which is helpful for people of all ages.”
Researchers taught study participants to challenge negative thoughts about dark winter months, and to resist behaviors, like social isolation, that affect mood. To compare the two treatments, study participants received either 30 minutes daily of light therapy, or two 50-minute sessions of CBT per week for six weeks. Two winters after the initial treatments, 46 percent of research subjects given light therapy reported a recurrence of depression. But only 27 percent of those who had CBT reported recurrence. While both treatments work, CBT is a longer lasting and potentially preventive treatment, according to the researchers.
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