So far we have been looking at bhastrika for kundalini, &, also done differently for health. We have been looking at nasikagra bhastrika. Nasikagra is referring to the nose. But it can also be done through the mouth, the mouth bhastrika being known as mukha bhastrika, & there are several forms of it.
I always advise students to exhale through the mouth if they are having difficulty doing a posture: for example, lying on the back bringing one or both knee/s towards the chest as you lift the head & shoulders up: pawanmuktasana/leg lock pose/reclining head to knee/gas relieving pose...whatever you know it as. And in cases of even more difficulty, I advise just pulling the knee/s into the body, blowing the air out firmly through pursed lips, at the same time, & pulling in the abdomen as it is done. But for a morning class, I suggest mukha bhastrika instead. In mukha bhastrika, the inhale is through the nose, but the exhale is done firmly & vigorously through the mouth, with the mouth being made into a hard beak shape, like a crow's beak, so the lips are pushed forwards. When you exhale, you pull the tummy back as you make a loud: "shoo!" sound. If you don't get the beak movement right, then you don't get the full effect.
This form of mukha bhastrika is deceptively profound. And, if your student is a smoker, or hasn't done much deep breathing, or is prone to breathing disorders, such as asthma...too much of it will really be too much. Take care here. Avoid if your student has bronchitis.
Mukha bhastrika increases alertness, so this is why I don't teach in it evening classes....it keeps one awake all night.
A few years ago I taught it very successfully for older people with dementia, alzheimer, psychosis, in a mental health unit. The people in the class could do nothing, could barely open their eyes, let alone speak or move the body...many were just there to live out their days in brain deterioration. Most sad. I felt that the best I could do was to "wake up the brain" as best as possible. It worked! It was a miracle! I did several things...& we gradually got around to be able to do a modified form of mukha bhastrika. It woke up many of the students brains, & they started talking to each other & moving around. The whole place changed. It woke up, became alive, even for those who could not do mukha bhastrika.
It is amazing for "waking up the brain", & my personal experience is that it seems to reduce inflammation, by cooling down the body. This is not the same as doing cooling breaths. Different. So, doing it in the morning with pawanmuktasana as described above, will have a very positive on blood sugar, as blood sugar problems are often an inflammatory disorder. Just doing both legs together 3-5x is enough, with mukha bhastrika.
Mukha bhastrika is another pranayama which is to be used a bit. Not a lot. Start just with the above mentioned pawanmuktasana pose. See for your self what the effects are like. Always remember: teach only what you know!