More than 80 percent of Americans rely on caffeine every day for a quick pick-me-up. Unabated stress, less-than-ideal nutrition, sleep deficits, too little exercise, and not enough time spent cultivating emotional and spiritual connections all deplete our energy stores, says Woodson Merrell, MD, Director of Integrative Medicine at Beth Israel Medical Center in New York, and author of The Source: Unleash Your Energy, Power Up Your Health and Feel 10 Years Younger (Free Press, 2008). If you don’t address the source of your fatigue, your dwindling energy stores can sap your immune system (making you vulnerable to colds and other infections), drain your libido, interfere with concentration, and leave you with little energy to enjoy social events.

Caffeine certainly gives you an immediate boost—and traditional caffeinated beverages tea and coffee have other health benefits such as lowering risk of diabetes, Parkinson’s disease, and colon cancer—but they don’t address underlying fatigue factors. Herbs and supplements, on the other hand, can restock energy stores by helping maintain the balance between the body’s energy-producing and energy-consuming mechanisms, says Merrell.

If your energy levels take a nosedive (especially if this is a new development), check with your health-care provider to rule out a medical cause (such as anemia, depression, or low thyroid hormone) before trying one of these five energizing supplements.

Ashwagandha

As with other adaptogenic herbs, ashwagandha has multiple nonspecific actions in the body that boost well-being, such as improving circulation, increasing nutrient absorption by cells, and helping the body use the stress hormone cortisol more efficiently so the adrenal glands don’t need to make as much.

How to take: 300–500 mg of a standardized extract daily. It may take 3–4 weeks of use before you notice an effect. This mild herb can be taken for as long as desired.

Citicoline (CDP-choline)

Citicoline results in clearer, more focused thinking. One recent Harvard study found that healthy men and women taking 500 or 2,000 mg of citicoline daily for six weeks showed increased energy in the part of the brain responsible for focus and concentration. Other research indicates that citicoline increases production of acetylcholine in the brain, a major neurotransmitter responsible for brain processing speed.

How to take: For a general brain boost, try the lower dose of 500 mg a day. Higher amounts (up to 2,000 mg) are safe and give a stronger mental boost. Results should be immediate, and this supplement can be continued for as long as desired.

Coenzyme Q10

Coenzyme Q10 is naturally concentrated in the mitochondria of cells—the powerhouses of energy production—where it helps in the complicated process of converting food into energy. As a supplement, it can boost energy and endurance levels for physical work or exercise. Particularly beneficial for people over 40, whose natural production of coenzyme Q10 has declined.

How to take: As little as 30 mg a day can increase energy levels; this is a good place for the average person to start. Safe to increase up to 200 mg a day, if desired. Coenzyme Q10 can take up to 2 months to have an effect.

Rhodiola

Also known as golden root, rhodiola has been shown in studies to improve cognitive function—particularly under stress—and elevate mood by facilitating production of serotonin. Although there is no research indicating that this is necessary, the traditional way to use this herb is to take it continuously for several weeks or months, then take a break of a couple of weeks before resuming use.

How to take: 200–600 mg of a standardized extract each morning, before you eat; start with the lower amount and take more for a stronger effect. If you experience insomnia, then lower the dosage. As with other adaptogens, rhodiola may take 3–4 weeks of use before you notice an effect.

Ribose

A naturally occurring sugar, ribose forms the backbone of the energy molecule (called ATP), which fuels every body function. When more ribose is present, muscle cells are able to create more energy. Jacob Teitelbaum MD, author of From Fatigued to Fantastic! (3rd ed. Penguin/Avery, 2007), recently published a study in the Journal of Alternative and Complementary Medicine which found that when people with chronic fatigue syndrome took ribose daily, energy increased an average of 45 percent after only three weeks. Although his research focused on patients with chronic fatigue syndrome and fibromyalgia, those with garden variety lagging energy levels also can benefit from this supplement.

How to take: 5 grams, three times a day, for three weeks; after that, twice a day for immediate energy needs. If you find yourself feeling hyperactive or if you develop insomnia, lower your dose.