As winter approaches, its short dark days can cause some people to slip into a deep depression lasting anywhere from a couple of weeks to the entire winter.
People suffering from this type of depression may have what's known as seasonal affective disorder, or SAD, a condition that develops from a combination of genetic vulnerability and inadequate light exposure, according to David Miklowitz, a University of Colorado at Boulder psychology professor. In Colorado, the peak period for SAD is November through March, he said.
"As the days get shorter and there is less light, people naturally tend to sleep more, feel lower and crave carbohydrates like sweets," Miklowitz said. "This condition is normal and happens to many people and is typically called the winter blues."
However, people with SAD suffer a serious depressive episode, which means it lasts two weeks or longer and they have difficulty functioning. They may have symptoms such as constant feelings of worthlessness, difficulty in concentrating or making decisions, feelings of guilt, an increase or decrease in sleep and appetite, severe insomnia, low energy, a lower sex drive and in extreme cases suicidal thoughts or actions.
For people suffering from winter blues during the long cold months, Miklowitz and other experts suggest people increase their exposure to light and expand their exercise routines as a first defense.
"Outdoor exercise, even if it's just a walk, is really, really important," Miklowitz said.
There is some evidence that exposure to light, especially in the morning, helps increase the level of serotonin available in the brain. Serotonin is a neurotransmitter believed to affect mood and sleep, according to Miklowitz. He suggests taking a walk at lunch in the sunlight or setting up one's home to let in as much light as possible. For example, people can arrange work areas next to windows, keep drapes open or set lights on timers to come on earlier in the morning, he said.
"If you're a person who goes to work at 7 a.m. and gets home at 6 p.m., you aren't going to get much exposure to daylight and this can really affect your mood negatively," Miklowitz said. "There really is no substitute to being out in natural daylight."
However if the depressive symptoms don't subside, don't hesitate to see a doctor, he said. "If this is a depression that is affecting your whole life, if it's making it hard to take care of your kids, or to go to work, or simply to get out of bed, it's time to go see somebody," Miklowitz said. "And it's better to see somebody sooner rather than later."
For those who do seek treatment for SAD, antidepressant medication, psychotherapy and light treatment are available, Miklowitz said. Light therapy involves being exposed to extra bright light, either from a light box or a special light visor, for a couple of hours during the day. While light therapy probably helps some, it's not a substitute for psychotherapy or medication, he said.
College students also need to be aware of the winter blues and SAD. "The thing to worry about with students is that their grades could fall as the days get shorter, and that they may be more susceptible to the effects of alcohol when their mood is low," Miklowitz said. "So they need to make sure they are getting exercise and that they try to keep some semblance of a regular sleep and wake cycle."
SAD has only been recognized as a medical condition since the mid-1980s, so researchers aren't certain what causes it, though most agree that fewer daylight hours trigger a reduction of mood-altering chemicals in the brain. People who have a history of depression also are more likely to get SAD, as are those living in the northern latitudes, he said.
Women are four times more likely than men to get SAD, a finding that is also true for depression in general, where women are two to three times more likely than men to be depressed, according to Miklowitz. At least one in six Americans will have an episode of clinical depression at some point during his or her life.