It's dark in the morning when you get up and dark in the evening when you come home. And it's all making you feel downright blah, maybe even teetering on depressed.
Sounds like the wintertime blues.
"It doesn't necessarily mean you're sad or down; you're just lacking in the push that all people need to get through the day," said Norman Rosenthal, a Maryland psychiatrist who studies seasonal conditions such as the winter blues. In the mid-1980s, Rosenthal and his colleagues at the National Institute of Mental Health coined the term "seasonal affective disorder," or SAD, for an extreme form of the wintertime blues.
About 20 percent of Americans start to feel down as the days get noticeably shorter, Rosenthal said. Some people start feeling their mood change as early as July, when daylight begins to grow shorter after the summer solstice on June 21. Most, however, first notice the change after they move their clocks back into standard time.
Psychiatrists and chronobiologists — scientists who study organisms' internal rhythms — say exposure to light, morning light in particular, is what makes the difference in mood.
"Light during the middle of the day is of no consequence," said Alfred Lewy, a psychiatry professor at Oregon Health & Science University who studies SAD.
Rosenthal, who wrote the book Winter Blues, agrees that morning light has been shown to relieve the blues but said light can be helpful any time. "Light can have an immediate boosting effect on energy and mood," Rosenthal said. "We don't really know why morning light works."
The role of light seems apparent in some geographical differences in the winter blues. According to Rosenthal, about 3 percent of Floridians report having the blues, while in Maryland, the number rises to 10 percent. In Fairbanks, Alaska — where the sun is up for only about four hours in December — it's about 19 percent. Regardless of location and for reasons that are unclear, women are three times as likely as men to develop the seasonal symptoms, Rosenthal says.
Why might the waning light cause lethargy, depression, social withdrawal and even hunger?
Some scientists suggest that those who experience winter blues are simply more sensitive to light and light deprivation. Others have shown that, in people with the blues, serotonin, the brain chemical involved in feeling satisfied, dips excessively when there is less daylight.
A widely accepted theory is that the limited winter light alters our biological clocks.
Humans run on an approximately 24-hour cycle that sets us up to be active during the day and to rest at night, says Michael Terman, a Columbia University psychiatry professor and president of the non-profit Center for Environmental Therapeutics.
Rosenthal said that in the evening, our brains start secreting melatonin, a hormone that signals to our bodies that it's dark outside. That happens a few hours before a person starts feeling sleepy.
Melatonin does not induce sleep, Terman says, but it appears to signal to the rest of the body that it is about time to rest.
In most people, sunrise often cues the brain to gradually stop secreting melatonin, Lewy says. Although that is not an immediate wake-up signal, once the hormone recedes from the system, we might tend to wake up spontaneously.
Because winter days are primarily dark, we want to sleep more and wake later. Life's morning obligations, however, don't change with the seasons. We might wake before we're biologically ready, then feel groggy and moody through the day.
Getting off daylight-saving time can help, but symptoms might worsen after a few weeks of standard time. "It's like having jet lag for four to five months," Lewy said.
An estimated 14 million people in the United States suffer from SAD, and for them, the wintertime blues tip into something quite debilitating as Rosenthal knows from experience.
He moved from subtropical Johannesburg, South Africa, which is sunniest in our winter months, to New York to begin his psychiatry residency in 1976. During that first winter, he noticed drastic changes in his productivity and mood. He couldn't meet deadlines. A natural writer, he was easily frustrated when he had to draft reports. When spring came, Rosenthal said, he seemed to wake up; he wondered why he had ever worried.