I always remember when I first joined this forum a kind lady said she used to do this
In your head,say 5 things you can feel,like, I feel my heart beating,i feel my hands on my chest, I feel my feet on the sheets,my head on the pillow,etc & repeat,it's simple but quite effective, I used to do it for anxiety,you can do it during the day too adding in 5 things you hear x