We have had a fairly mild winter thus far. Still, “mild” means little to those among us with a particular sensitivity to our common overcast, gray skies. It just reminds me that, even in the 21st century, we are not insulated from nature.

One of my favorite young colleagues and I were talking about the effects of day-after-day cloud cover on friends and students. We were chuckling over the reaction of one of my mapping students at the turn of the last century. After a dark week, we were discussing a set of maps laid out on one of the big tables in the lab. Suddenly, the sun broke through the sky and our south-facing windows, splashing brilliantly across the maps. The student unhesitatingly threw himself across the maps and into the light. He was nearly in tears. “You don’t know, man, those clouds made me so depressed I’m just barely hanging on,” he said. “And my mom goes nuts if the sun is gone away for a week.”

For a surprising number of people this is not even remotely funny. It has been called “winter depression” and “seasonal depression,” but over the last four decades it is generally called “Seasonal Affective Disorder” or “SAD.” A fair number of our friends right here in Paradise have already been bummed out to some degree.

In antiquity, physicians observed seasonal variations in mood. Belief was that mania (most prevalent in summer) was caused by heat, while depression (mostly winter) was caused by cold. In our time, researchers tie SAD to day length, amount and type of light, and falling temperature. SAD is most common in northern latitudes and polar regions, often beginning in November.

Light‑sensitive people begin to feel almost constant fatigue and drowsiness, commonly sleeping 10 to 12 hours a night, when they can get away with it. For many, a normal workday schedule becomes impossible. Sadness, irritability, anxiety, lack of concentration, social withdrawal and decrease in libido are common. Throw in a dose of guilt and self‑blame, for not being able to meet everyday expectations, and you have a sense of what SAD does to people.

Women make up about 75 percent of those treated. Children suffer, too, but their symptoms are typically milder. Among youngsters, SAD affects sleep, appetite and friendships. It is often associated with headaches and problems in school.

SAD sufferers often develop huge cravings for carbohydrates. In severe cases, winter weight gain may exceed 30 pounds. This is not unexpected, really – it simply flows with Nature’s rhythm. Consider that eating carbohydrates, gaining weight, decreasing activity and socially withdrawing are all energy‑conserving behaviors of humans in winter. Sadly, these days we consider such behaviors disruptive and detrimental.

Melatonin is the hormone which signals length of day, seasons and mating urges in many animals. Understanding that its production is triggered by light through the eyes, light‑sensitive people can be helped. If you are one of them, taking the most-recommended actions, below, may get you through winter better than “normal” folks. While physicians will prescribe drugs in very extreme situations, help generally takes a couple forms; outdoor activity and light therapy.

It is simple these days to fill a room in your house with the colors of sunlight using full-spectrum fluorescent tubes. Reading and relaxing for an hour or so in this more natural light is often very helpful. The SAD Association (www.sada.org.uk) has three standards for such lighting. A color rendering index (CRI) of 90 or more indicates that a full-spectrum tube is reproducing sunlight in proper proportions. Light in the green region of the sun’s spectrum seems particularly helpful. In addition, a light source should have a brightness of around 10,000 lumens (about 150 watts). Add to that a Kelvin rating of 5,000K (a sufficient level of light intensity), and you will probably be feeling spring. Good lighting, and its proper use, may even inspire play – never a bad thing.

There are simple day-to-day suggestions for managing those moments in battle with winter depression. Spend an hour a day outdoors in daylight; stay in rooms with big windows and stand by them staring at the sky; eat the foods you crave, without guilt; and remind yourself that you are just flowing with Nature’s rhythm.

No surprise here: SAD symptoms will be alleviated by a trip south to longer days and sunnier climes. If things get too far out of hand with someone close, go to Mexico for a few weeks. If your supervisors object, tell them it was my idea.

Finally, remember that, come spring, SAD sufferers will generally return to themselves.