There has been a lot of really good research on the positive effects of deep, slow breathing. It is the opposite of what we tend to do in our everyday lives, as we run around trying to do too many things in very little time.
When we breathe fast, which tends towards shallow breathing (ie into just the top of your lungs), the sympathetic nervous system is activated. This is the nervous system in charge of our 'fight or flight' reflexes, associated with stress. In the short term this is fine - if we start to cross a road and don't see a car coming then we need a quick 'flight' response to get ourselves out of the way. What is happening in modern life however, is that the stress response is activated for a lot of the time. This leads to long term, chronic stress which effects health in terms of narrowed arteries, higher blood pressure, insomnia, IBS, migraines and a whole host of negative health conditions.
The opposite of this high anxiety state is when the parasympathetic nervous system is in control. This is our 'chilled out' state which allows blood vessels to dilate, blood pressure to come down, good circulation, blood flow to the brain and improved digestion. This is the state we, ideally, would be in most of the time.
In order to achieve this state we need to allow ourselves to breathe slowly and deeply - into the bottom of the lungs. Setting aside a minute or two a few times a day for deeper breathing will help your body recognise this state as a good alternative to the high-stress one. It will give your circulation and hormones a chance to return to balance for optimal health. When your body is functioning at this de-stressed level it allows for healthy cell growth and organ repair meaning less illness and a better immune system. And that's on top of just feeling great!
Five breaths per minute is the amount the research indicates is a good, slow breathing pattern. In order to get it right, you could lie down and put one hand on your chest and one just above your navel. Try to breath in and out from the lower abdomen. This means only the lower hand should move with your body - the hand on your chest should remain still because the upper chest isn't moving at. If it's too slow for you to start with, just try to use some slower breaths and practice making them long and slow as possible and try syncing with the video above.
With practice, you should be able to slow your breathing wherever you are - you don't have to lie down. While you're waiting for the lift, at the photocopier, in a meeting or sitting on the bus. Doing this as many times as you can during your day will have incredible long term health benefits.