Recently I have been having success (I feel and think) in the double breath technique as prescribed by Yogananda. I got the sensation of energy gently pulsing up back side of head and in face which was very enjoyable (like a sprinkling of refreshing rain on a burning desert!) Are there guidelines for how long we should do this for. i,e min and max time, to avoid too much energy being aroused in body with nowhere for it to go.
Yes, it is indeed an enjoyable technique. The exact nature of the experience can vary from person to person, and even from time to time with the same person. So don’t be surprised if yours changes at some point.
There’s no minimum length of practice (even just one breath is good). As for the maximum length, it’s more about monitoring the effects than the time. Some people hyperventilate with too much double breathing; don’t continue the technique if you begin to feel light-headed. Also, because the technique moves a lot of energy, there can be times when too much double breathing makes you feel agitated, irritable, or anxious; that’s a sign to stop.
So be watchful of the effects, because it’s definitely possible to overdo double breathing. It should always feel good and calming-yet-energizing. If it doesn’t feel that way, don’t continue with that session.