You know that getting a  good night's sleep is vitally important for your mental and physical health, mood, and even brain function. But what if you just can't fall asleep? We all have trouble sleeping at times in our lives, and for some people, it's a constant battle.

But there's a simple and amazingly powerful tool that will not only help you sleep, it will steady you in times of stress, help you cope with cravings and other bad impulses, and help you avoid reacting badly when things upset you. Over time, it can help with digestion, lower your heart rate, and lower your blood pressure. And it only takes about a minute to do. 

The exercise is called 4-7-8 breath, and it's a form of the ancient yoga practice of breath control (pranayama). It was popularized in this country by Dr. Andrew Weil, who says it's more effective for controlling anxiety than anti-anxiety medications.

Here's how to do 4-7-8 breathing:

1. Begin by exhaling all the air in your lungs through your mouth with a whooshing sound.

2. Place the tip of your tongue on the roof of your mouth, right where the ridge of flesh meets your two upper front teeth. Keep your tongue there through the entire exercise, even when you're exhaling. 

3. Breathe in through your nose for a count of 4. Hold your breath for a count of 7. Breathe out through your mouth with a whooshing sound for a count of 8.

4. Repeat the entire cycle four times.

If holding your breath for a count of 7 or breathing out slowly enough to get through a count of 8 is difficult, then speed up the count, but don't change it--the 4, 7, and 8 proportion is important, Weil says. Over time, as you get better at it, you should be able to slow the exercise down, which increases its benefits.

Weil advises doing this exercise at least twice a day--more if you like. Don't go beyond four breath cycles at a time for the first month or so. Once you get really comfortable with it, you can increase it to eight cycles, but that's the maximum. If you want to increase the exercise's effect, slow down the count instead of doing more cycles.

He also says you should do the exercise for four to six weeks before you start trying to use it to induce calm or help you fall asleep, but you may not need to wait that long. Some people who have trouble sleeping find they get instant results with the 4-7-8 breath technique. The health benefits, such as lower blood pressure, come with continuing this practice over time. If it works for you, it could become a lifelong habit.

I've done lots of pranayama in yoga classes, but I didn't know about the 4-7-8 technique before today. I've tried it out and it does indeed cause my whole body and mind to relax. Now that I do know about it, I plan to start using it on a daily basis, starting tonight. How about you?

Here's Weil, demonstrating and leading the technique: