03/28/2008 02:48 am ET Updated Nov 17, 2011

Winter Depression (Otherwise Known As SAD)

A woman I'll call Cathy came to me recently for a foot problem, but ended up talking about very different problems. "I've just had it with this winter," she told me. "I just can't get up the energy to get my work done. I can't concentrate, even when I do have the energy. I don't feel like talking to friends. I cry at the drop of a bucket."

"Is it just this winter, Cathy?" I asked her. "Or is it every winter?"

She thought about that. She shrugged. "Maybe it's even worse this time, but it's every winter, pretty much. I guess I've come to expect it, but I've never gotten used to it or gotten over it. When it gets cold, I turn into a different person."

Countless people feel a little like hibernating when cold weather arrives, but many suffer from a syndrome that makes them experience true depression during the winter. It's called Seasonal Affective Disorder (SAD), and, chances are, you or someone you care about it has it.

SAD is thought to be caused by decreased exposure to sunlight and causes symptoms identical to those of major depression from other causes. They include low mood, tearfulness, inability to concentrate, impaired sleep patterns, weight gain, irritability and even thoughts of suicide.

In Alaska, over eight percent of the population is thought to suffer from SAD. Many other states have rates of three or four or five percent. Think about that: We may be talking about over ten million Americans.

According to Keith Ablow, MD, the Fox News psychiatrist "SAD is an under-diagnosed condition that is responsible for a tremendous amount of psychological distress, but also a big price-tag in terms of decreased productivity of folks who think they're just 'down,' but are really fighting a real psychiatric disorder. People who have always 'hated' the holidays or who 'can't stand' February should start to wonder whether that's them speaking or an illness speaking for them."

Ablow has treated executives whose work performance plummeted during the winters, students whose grades fell, couples who argued ceaselessly during cold months and got along pretty well during warm months, even celebrities who couldn't perform when New York winters got them down.

There's something the millions of Americans battling SAD should know. It's highly treatable, often without medication. Here's the prescription: bright light. That's right. "Owning a special high intensity light that you put on your desk can replace the sunlight you're missing and restore your sense of wellbeing", adds Dr. Ablow..

Sound too good to be true? It isn't.

"It's amazing to me that so many people still don't know that these lights [widely available from companies like LiteBook and Northern Light Technologies], can actually have great positive effects on the winter blues. Using one daily, for a short period of time, maybe while reading the newspaper or having a cup of coffee or doing some work on the computer, can change people's lives. If enough people had them, it could actually have a very significant and very positive effect on public health.", says Dr. Ablow.

Here's a prediction: Watch for these bright lights to end up having positive effects on alertness, concentration and mood not just for people with the winter blues, but for millions more who may suffer low level mood disorders that are due to chronic lack of exposure to light. So many of us wear sunblock and sunglasses all the time, opt for surfing the Internet over surfing for real (or doing anything else outside), and travel from the car to the office and back again, that I think we may have an undiagnosed epidemic of sunlight deprivation to contend with.

Bright light therapy isn't to be used by certain folks with eye conditions or skin conditions that prohibit exposure to high intensity light. They can also rarely cause someone vulnerable to bipolar disorder to experience too much energy and even manic symptoms. And sometimes medications are indeed necessary to stop SAD. But for millions of Americans, these bright lights are just what the doctor ordered.