Nostril breathing

How to use the nostril individually?
They function somewhat like an air conditioning unit and a furnace, turning on and off, switching back and forth from heating to cooling every two and a half hours, keeping your temperature normal and your energies in balance. 
Your pituitary gland the master gland of the body serves as the thermostat to control the stitches. 
The left nostril draws in the cooling, soothing, mind-expanding energy of the moon. It is the water element. 
The right nostril draws on the sun's energy. This is for vitality, activity, and mental alertness, it heats the body. 
You can experiment right now and find out which of your nostrils is working. Place a finger underneath your nose and gently exhale.
You will discover that the air flows mostly out of only one nostril. 
The right nostril controls our energy level and the left controls our emotions. 
Consequently, if we are tired, breathing long and deep through the right nostril will give us added energy. 
Breathing through the left nostril can calm us down when we are upset and emotional, angry, frightened, or just generally disturbed. 
Although your body has its own rhythm for automatically alternating nostrils for breathing, there are times when you will benefit from consciously controlling this function. many pranayams use one, both, or alternate nostrils, depending upon the effect desired.
If you're upset, angry, agitated, mentally emotionally disturbed, or just plain moving too fast and feeling pressured and stressed out, try this:
Find a private place where no one will disturb you, and take five minutes for this pranayam. Sit with your spine straight. Using the thumb of the right hand, keeping the other fingers together, and pointing straight upward like antennae, close your right nostril. Begin long deep breathing in and out through the left nostril only. Twenty-six long deep breaths through the left nostril will do the job. When you are calm, then you can decide how to deal with whatever situation requires your action, because you won't be triggered into an emotional knee-jerk response. 
Alternate nostril breathing
Here's a breathing technique using alternate nostrils to soothe and calm and at the same time energize your whole nervous system. It works because the energy of your nervous system is directly proportional to your breath. In only three to five minutes you can revitalize your whole nervous system. This particular technique can come in handy when you feel off-center and yet have to function at your job or in school or at home. Suppose you have an important business meeting scheduled but you're feeling extremely nervous and irritable. This pranayam can help you calm down so you can be effective in your communication at that meeting. 
Here's how:
Sit comfortably with your spine straight. Use your thumb and index finger on the right hand. Make a "U" of your thumb and forefinger. Use the thumb to close the right nostril while breathing in or out through the left nostril, and the index finger to close off the left nostril while breathing in or out through the right nostril. Keep your other hand in your lap, or resting on your left knee. 
The breath sequencer goes like this:
Close the left nostril, and inhale deeply through the right nostril. At the completion of inhalation, close the right nostril and exhale through the left one. 
Now inhale through the left nostril fully and deeply. Then close the left nostril and exhale through the right one. 
Again, inhale through the right nostril and exhale through the left. 
Continue this breathing pattern for three to five minutes. 
Breathe fully on both inhalation and exhalation cycles. After three to five hands and exhale through both nostrils. 
Relax and feel great!