It's often hard to get to sleep due to the fact that we haven't released the stress that has built up in us all day.
In addition to left nostril breathing, use water and massage.
Sit on the edge of your bathtub and turn on only the cold water. Put your feet under the cold running water. Briskly massage your feet using your feet: rub your feet all over each other and rub the soles together. After you've done this for 30-60 seconds, roughly dry and stimulate your feet with a coarse towel.
Now enjoy your deep sleep!!