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In 1984, Norman Rosenthal, M.D., piloted a milestone study correlating reduced exposure to sunlight with incidence of SAD. Sunlight triggers the production of serotonin, a neurotransmitter in charge of boosting your mood. When the sun goes down at night, serotonin converts to melatonin—a hormone that makes us sleepy. The next morning, the arrival of daylight converts melatonin back to serotonin, giving us the get-up-and-go we need to make it through the day.
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What do carbohydrates have to do with all of this? In Rosenthal’s 1984 study, 79 percent of participating SAD sufferers complained of heightened carbohydrate cravings. And there's a reason your body wants them. Consuming carbohydrates boosts the availability of the amino acid tryptophan, which is what sunlight converts to mood-boosting serotonin and vitamin B6. The problem is, you’re not consuming anything that contains high levels of tryptophan, says Gedgaudas.
The best sources for tryptophan are seafood, poultry, grass-fed meats, leafy greens, and green vegetables such as asparagus and broccoli. But because SAD causes you to crave refined carbs, you eat less of those healthy foods, and as a result, your body has no tryptophan to turn into serotonin. As a result, your energy levels plummet and you feel bad. "So you feel tired and you feel out of it, and you feel like you want to be sleeping. You’re depressed," she says.
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While Gedgaudas thinks refined carbs should be eliminated permanently, if that's not an option for you, it still is a good idea to cut back in the winter, particularly for SAD sufferers. Even though refined carbohydrates give you energy and provide a short-term mood lift, they're really just a "short term fix," Gedgaudas says. "White rice, potatoes, cereal, pasta—you can kind of look upon those as being like paper on a fire," she says. They tend to flood your system with tons of energy all at once, and then you experience a blood-sugar crash that causes you to crave more carbs, and the cycle goes on and on. Even carbohydrates such as brown rice and beans can have the same effect, she says, but at less severe levels. What's more, she adds, "grain-based diets are part of the reason people are so deficient in tryptophan. Grains don't contain this essential amino acid, and eating grain-based diets depletes tryptophan." (Here's exactly what one woman ate to get her blood sugar levels under control.)
Instead, Gedgaudas suggests a more efficient energy source: fat—a long-lasting, even-burning fuel. Healthy fats, such as organic coconut oil and ghee (Indian clarified butter), along with grass-fed meats provide all the tryptophan your body needs at a consistent level, keeping your mood elevated. In fact, a study in the Journal of Affective Disorders found that giving volunteers tryptophan supplements was as effective as light therapy for treating SAD.
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The fuel switch is not always easy. Cravings for starchy or sugary treats can be intense for the first few days, but that goes away, says Gedgaudas. While you're transitioning, add healthy fats such as coconut oil to healthy complex carbohydrates; doing so will slow down your body's absorption of carbohydrates, resulting in a longer, steadier energy burn. "Taking omega-3s for SAD I think is quite important, as well," she adds. They improve your body's serotonin receptors and help ward off depression.
Of course carbohydrates are just one piece to the SAD puzzle. There are lots of other ways you can lighten seasonal depression, if giving up carbs isn't doable. Getting more sunlight is essential, whether it’s through spending more time by the window, incorporating a walk everyday or investing in a full spectrum lightbox for your desk at work. The old healthy living standbys have a lot of sway here, too. Don’t forget to get enough sleep and enough hilarious downtime with friends. And exercise! After all, there's no better mood-lift than a post-workout endorphin rush.