Those of us with blood sugar issues want to be especially careful of our mood swings and mental health. So we want to pay particular attention to seasonal affective disorder (SAD) - a common malady during the long winters for folks living in the northern parts of North America. The antidote? Using a light therapy box during these darker months.

It's the lack of adequate sunlight exposure that's common during colder weather that brings on SAD - a type of depression. And light therapy boxes, also known as light boxes, bright light therapy boxes and phototherapy boxes, have been extensively researched by scientists at the Mayo Clinic.

I struggle with SAD and have been looking into light boxes for a couple years now. So I was particularly interested in what Mayo has to say, and thought you might be interested as well. They say that while these boxes are designed do the same thing, one may work better for you than another. They suggest studying the options before you buy one, to be sure you're getting the light therapy box that best suits your needs.

The Mayo Clinic has done extensive research on this subject as well as on the types of boxes available. The light from a light box mimics outdoor light. This causes a chemical change in the brain that lifts your mood and eases other symptoms of the disorder. Light therapy can also be used to help adjust daily sleep cycles (circadian rhythm), which may play a role in mood. Light boxes are generally used for 30 minutes or longer each morning, with bright light shining indirectly toward your eyes.

You can buy a light box over-the-counter, without a doctor's prescription. Internet retailers, drugstores and even some hardware stores offer a variety of light boxes. Or, your doctor may prescribe a particular light box. In some cases, health insurance companies require a prescription from a doctor to cover the cost of a light box.

Different light boxes produce different types and intensities of light. They also come in different shapes and sizes and have different features. Light boxes are all designed to be safe and effective, but they aren't approved or regulated by the Food and Drug Administration. Research on light boxes is still limited, so it can be challenging to sort out which ones are safest and likely to work best for your particular needs. That's why it's important to understand your options before you choose one. Here's what to consider:

•  Is the light box made specifically to treat SAD? If a light box isn't specifically designed to treat seasonal affective disorder, it may not be safe or may not relieve your depression. Some light therapy lamps are specifically designed for skin disorders - not seasonal affective disorder or depression. These light boxes emit ultraviolet (UV) light that could damage your eyes if used incorrectly.

•  How bright is it? Some light boxes are brighter than others - which means you need to use them for less time each day than dimmer light boxes to achieve the same effect. Look for one that provides the right intensity of light when you're a comfortable distance away. For example, it may be effective to use a light box that produces 10,000 lux (a measurement of light intensity) 12 to 14 inches from you for 30 minutes each morning. However, using a box that produces 2,500 lux at the same distance may take two hours or more to achieve the same effect.

•  How much UV light does it release? Light boxes for seasonal affective disorder are designed to filter out most UV light, which can cause eye and skin damage. Some light boxes produce more UV light than others. Look for a light box that emits as little UV light as possible at high intensity. If you're not sure about the UV light exposure, contact the manufacturer for safety information.

•  Does it use LEDs (light emitting diodes)? Traditionally, light boxes have used fluorescent or incandescent lights. But now some manufacturers are selling light boxes with LEDs. LEDs can produce light in a narrower, more targeted wavelength. LEDs are also more efficient and lighter weight than standard lights, and appear to work just as well.

•  Does it emit blue light? White light is the standard type of light used in light boxes. But some light boxes give off blue light with a shorter wavelength. Some research shows blue light may be slightly more effective at reducing seasonal affective disorder symptoms than other types of light, but more research is needed to tell whether it's a better option. Although eye damage from using a light box is uncommon, blue light may pose a greater risk of harming your eyes than does white light. To help reduce this risk, don't look directly at the light source in any light box.

•  Is it the style you need? Some light boxes look like upright lamps, while others are small and rectangular. Some light boxes are sold in pairs that are used together. You can even buy a battery-powered light therapy device attached to a visor, but it isn't clear yet whether this type of light works as well as a standard light box.

•  Can it be positioned appropriately? Think about where you'll want to place your light box. Keep in mind, most light boxes need to be positioned within 2 feet of you. Make sure the light box you choose can be positioned appropriately.

•  Is it the type of box that simulates sunrise? Some light boxes simulate dawn - they turn on in the morning while you're asleep and gradually get brighter until you wake up. This may help regulate your sleep patterns if used correctly. However, keep in mind that to relieve depression you need to be exposed to bright light with your eyes open for 30 minutes or longer.

•  How much does it cost? Prices vary, from about $100 to as much as $500. Since health insurance plans don't always cover the cost of light boxes, you'll want to check with yours to see if your benefits will cover the cost.

•  Features. Some light boxes are operated with a simple ON and OFF switch. Others offer a variety of features, such as adjustable brightness, programmable timers, clocks, carrying cases, stands, wall-mount options and extended batteries. Decide whether any of these features are going to help you get the most out of your daily light therapy sessions.

•  Does your doctor recommend it? Before you purchase a light box, talk to your doctor, mental health provider or pharmacist. Ask about the light box you're thinking about buying. He or she may offer additional guidance or tips to make sure that treatment with a light box is safe and as effective as possible for you.