Choir singing is known to promote wellbeing. One reason for this may be that singing demands a slower than normal respiration which may in turn affect heart activity. Coupling of heart rate variability (HRV) to respiration is called Respiratory sinus arrhythmia (RSA). https://www.ealisboa.com/great-pick-BERKLEY-POWER-WORM-7-100-PACK-super-buy/