Once in bed, there are several recommended breathing techniques designed to slow down body functions that keep you tense and anxious. Slow, deep breathing slows the heart rate and makes it easier to drift off to sleep.
4-7-8 is one such breathing technique.
With mouth closed, breathe deeply in through the nose for four seconds.
Hold for seven full seconds.
Breathe back out for eight seconds.
Repeat four to eight times.