You may want to try breathing exercises to help to strengthen the lungs as well as relax for sleeping.
I have COPD and use one of two methods (depending on how tired I am).
First - relax your muscles. Especially the shoulders.
1 Breath in for four seconds, hold for four seconds and out for four seconds.
or
2 Breath in for six seconds, hold for seven seconds and out for eight seconds.
Do this three times then increase the time. ie in for seven, hold for eight and out for nine.
Three times and increase the time again. By then I am usually asleep.
Works for me anyway - good luck.