If you are feeling tired and sluggish, you might be suffering from magnesium deficiency.

Our great grandparents obtained 500 milligrams of magnesium daily from their diet. Today, our soil has been so depleted of this crucial mineral that the amount we normally get from food has been diminished to under 200 milligrams a day.

In addition, the magnesium we do get is also diminished by eating sugar, living a stress-filled life, working out too hard, and taking certain medications and drinking too much caffeine.

Magnesium is the most important mineral we need in terms of day-to-day function, and yet half of us are deficient. Magnesium deficiency is most often caused by lifestyle factors, including a diet that's high in processed foods, alcohol abuse, and Type 2 diabetes.

Here are signs that you might be deficient in magnesium:

Irritability. According to Health, low levels of magnesium might increase irritability and anger. If there isn't enough magnesium in your system, your brain can't control vital neurotransmitters that influence mood. You might find it hard to cope with daily activities.

Nausea. Magnesium is needed to regulate muscle mobility so your gut might not function optimally if levels are low. Low levels of this crucial mineral might cause nausea and vomiting. A deficiency can cause severe digestive discomfort.

Decreased appetite. Losing your appetite is an early warning sign of magnesium deficiency. The mineral is used for normal muscle and nerve function, including the muscles needed for digestion. A deficiency might also disrupt hunger hormones such as leptin, reducing the desire to eat.

Fatigue. Low magnesium levels can lead to lethargy and exhaustion and affect you mentally and physically. That's because magnesium binds with adenosine triphosphate, or ATP, to power up the cells in our body.

Numbing in extremities. Since magnesium affects nerve function, if you find you are getting numb or have tingling in your extremities, it might be because of a deficiency. Magnesium helps regulate calcium in nerve cells to facility nerve transmission. Without enough magnesium in your body, you can't regulate the calcium levels that cause peripheral nerve degeneration.

Constant headaches. Magnesium is so important in the management of headaches, especially painful migraines. It helps dilate blood vessels in the brain, so low levels of the mineral can negatively affect blood flow to the area. Taking a magnesium supplement before going to bed after imbibing can help prevent a hangover, said noted headache expert Dr. Alexander Mauskop.

Poor sleep. Magnesium helps regulate the neurotransmitters that affect sleep, according to Health, and maintains healthy levels of the sleep cycle hormone melatonin. Magnesium can also help reduce stress.

Dr. David Friedman, the best-selling author of "Food Sanity, How to Eat in a World of Fads and Fiction," said "magnesium plays a vital role in converting food into energy, protein synthesis, regulating the nervous system and repairing our DNA."

"Without magnesium, our muscles and nerves couldn't function, or brain wouldn't work, and our bones would turn to Jell-O!" he said. The foods that are richest in magnesium include red bell peppers, spinach, watercress, dark chocolate, and cucumbers. Chia and pumpkin seeds are also rich in magnesium.

Experts recommend between 500 and 600 milligrams of magnesium daily, and because we get only about 200 milligrams from foods, most of us need to supplement with between 300 to 450 milligrams of magnesium glycinate or magnesium citrate, forms of magnesium that are easily absorbed by the body. Always check with your healthcare provider before taking supplements.