Fall's time change is a great but gloomy time of year. The great part? You get an extra hour's sleep when Daylight Saving ends in November. (You spend every second in bed? Us, too!) The gloomy bit: Until March, when Daylight Saving returns, the days will be short and dark.

Put another way: There goes the sun, here comes the Great Winter Vitamin D Deficiency.

Even in summer, few North Americans get enough sun to activate your skin's vitamin D3 factory for long (why it's called the “sunshine vitamin”). In winter, vitamin D deficiencies are way worse. The sun's rays are too wimpy to have much effect. Yet D3 (vitamin D's most active form) is essential. It protects you from brittle bones, hypertension, heart attacks, strokes, diabetes, certain cancers, and more -- as if this list isn't plenty important enough. Vitamin D even perks up your memory. So stock up.

• Start with food. Canned salmon is terrific: 500 IU of D in 3 ounces. Canned tuna's good, too: 200 IU in 3 ounces. Each glass of D-enriched OJ and nonfat milk adds another 100 IU.
• Take a supplement. Swallow 1,000 IUs of D3 a day, 1,200 after 60. Taking it with your omega-3s boosts absorption. Taking vitamin D with a meal helps, too. (Find out which meal will help you absorb more vitamin D.)
• Get a blood test for D3. It's the only way to know how you're doing. If it's low (below 50), adjust and recheck in 3 months. Your payoff: Adults with the highest D3 have the fewest "cardiometabolic disorders," a cluster of health problems that includes heart disease, diabetes, and metabolic syndrome. (Just don't take too much vitamin D. Here's why.)

Happy ending: Right after Daylight Saving stops, research shows heart attacks drop 5%.

Not a morning person anyway, but even less so when it's dark outside? Try this.