Breathing exercises

Sitting with their right hands over their faces, the group practise a breathing
exercise.  Many of them have their eyes closed, concentrating on their
breathing.  After a few minutes, the tutor chimes a bell and the group drop
their hands into their laps and settle into their sitting position.

Alternate nostril breathing

Breathing exercises can be extremely helpful in promoting physical relaxation, through the process of slowing and deepening the breath.  They are also a useful adjunct to meditation as a preliminary practice. 

It can be especially useful to employ a breathing exercise in the morning before the demands of your day begin.  It may help you become fully awake and refreshed and ready to start the day.

At other times of day, breathing exercises can calm you if you are feeling worked up, or can encourage clarity if you are feeling flat and lacking in energy.  Breathing exercises may also have therapeutic benefits, such as helping with pain relief, insomnia, and emotional distress.

Relaxing into Meditation, Chapter 3, page 13