Breath 4 7 8 was introduced and invented by Dr. Andrew Weil, who used this type of breathing especially for anxious people. One needs to practice this breath at least twice a day and after a month one can start using it for specific situations. It helps to fall asleep, calm down and relax.
Enjoy your breathing.

Another great breath technique for calming ourselves and helping to sleep, especially when one feels overwhelmed. is
Bhramari Breath..