If you feel wiped out all the time, you’ve probably tried all the obvious solutions—such as getting more sleep and physical activity. But if you can’t seem to shake your exhaustion, you may have a cortisol deficiency. Cortisol is not a well-known hormone, but it plays a major role in helping our bodies manage stress, control inflammation and sustain physical and emotional energy. Cortisol is produced by the adrenal glands, two deep-yellow organs that look like mushroom caps and sit atop each of your kidneys. This hormone is a real workhorse—it helps your body maintain normal blood pressure, heart function and metabolism and promotes healthy immunity. Trouble starts, however, when your cortisol levels are too low. You’ll be hit not only with fatigue but also possibly other problems such as depression and muscle and joint pain.

Diagnosing a cortisol deficiency—also known as “adrenal fatigue”—can be tricky because cortisol levels naturally fluctuate throughout the day. In a healthy person, cortisol should be highest first thing in the morning and decline to the lowest level just before bedtime. If you have a deficiency, however, cortisol levels often don’t follow this pattern—for example, levels may surge later in the day. Because a onetime blood or urine test will often miss these changes in cortisol levels, I prefer a saliva cortisol test, which relies on four samples collected during a single day—upon awaking, around noon, early evening and bedtime. Saliva cortisol testing can be ordered by any licensed physician.

When cortisol levels are low, the doctor may prescribe a low-dose (5 mg to 15 mg daily) cortisol replacement, such as Cortef.* But cortisol replacement isn’t for everyone. If you have high blood pressure, it can sometimes worsen that condition…or it may cause glaucoma, cataracts and/or water retention. For these individuals—as well as anyone with a mild cortisol deficiency—it’s worth considering botanical medicine, which doesn’t have these side effects. Ashwagandha…rhodiola…and astragalus (alone or in combination) are good choices and are usually taken for three to 12 months. Dosing varies based on your individual need and sensitivity. People with low cortisol production also may benefit from taking supplements of the nutrients that are essential for healthy adrenal function—vitamin C (1,000 mg daily)…vitamin E (400 international units daily)…pantothenic acid, or vitamin B-5 (250 mg to 500 mg daily)…and B-6 (50 mg daily). (Check with your doctor first if you take medication, since these herbs and vitamins can interact with some drugs.) You may take these supplements for several months…or even indefinitely. People who use prescription cortisol replacement sometimes take it for life—similar to, say, thyroid replacement—while others use it for a shorter time, depending on how their cortisol levels respond. I usually retest cortisol levels after three to six months. Work with your doctor to see what’s best for you. And remember: Stress reduction, regular sleep, moderate exercise and avoiding caffeine are also essential to normalize cortisol levels.

*For high cortisol levels, see an endocrinologist—you may have a different adrenal gland disorder, such as Cushing’s disease.