Recently i noticed a certain regularity while doing my meditation. 10 minutes in, there come a phase where my breathing intuitively becomes very deep and fast, accompanied by physical sensations of heat or energy (?) and immediately after that my beathing becomes very slow and calm.
I don't really see a problem here, just wanted to know if others have noticed a similar regularity while meditating?
Great that good things are happening because of your meditation practice What you are describing is quiet natural; breathing will be affected; it is normal that it slows down. The "heat or energy" that you experience is prana flowing through. It is this ingredient that is the main purifying factor when it comes to the nervous system. If you click on Yoganis lessons under "Breath suspension" in the topic index here: http://www.aypsite.org/TopicIndex.html you will see many examples of this.
Here is a lesson that describes the breathing slowing down:
Are you doing Spinal Breathing Pranayama? If not - it might be a good idea to add it. It has a great stablizing effect and together with Deep Meditation it is the two main tools in AYP.