The reason you're fumbling on presentations or not coming up with brilliant ideas at work may have nothing to do with your IQ or lack of sleep, and everything to do with the amount of stress you're under. Cortisol, a hormone released by the adrenal glands during flight-or-fight moments, like when you're on deadline, provides the body with a jolt of energy and helps it experience lowered sensitivity to pain, higher immune-system function, and a heightened state of mental awareness. But high levels of cortisol lingering in your body may cause damage to your gray matter over time, destroying the cells of the hippocampus, a part of the brain responsible for memory. Furthermore, if the adrenals are always pumping, they can burn out; the resulting drop in energy and fuzzy mental state are reflections of low cortisol levels.

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"[A cortisol spike] is very useful when you're being chased by a tiger but harmful when you sit behind a desk," says Matthew Becker, lead practitioner at Pharmaca, a chain of pharmacies based in Colorado that provide both Western medicine and traditional herbal remedies. While you could pop a Provigil and stay sharp for a few hours, there's a holistic way to treat the underlying problem. Herbal adaptogens (natural compounds that allow your body to adapt to stressful situations) can help bring cortisol levels back to normal. "I have seen rhodiola stop a panic attack in two minutes," says Becker. Other cortisol adaptogens include eleuthero (often called Siberian ginseng), panax ginseng, and American ginseng, all of which are believed to regulate cortisol levels and are available in multiherbal energy supplements, such as Natura's Power Adapt ($26).

"Adaptogens are certainly extremely effective in helping the body cope with stress," says Michael Byrne, a Seattle-based naturopathic physician. "But when it comes down to it," he adds, "getting enough sleep and relaxing are still the best ways to fight stress."