My son’s psychologist recommended a few simple techniques for helping him to relax, which I shall share here.
Hug for 20 seconds, Hugging releases a hormone called oxytocin, often called the “love hormone” which has been “linked to a sense of calmness and wellbeing”*
Deep or slow “belly breathing“. You and your child lie down on your backs with a cushion under your heads, and tell your child to breathe in deeply through their nose until they can feel their belly going up. Then you both breathe out through your mouths, almost blowing the air out in one long breath. They could blow a feather or windmill (pinwheel). See breathing techniques for children for more information. Do this several times building up to five minutes. You or your child may feel a little dizzy or lightheaded after this so make sure you are lying down. Alternatively, if they find this difficult teach them to hold their breath for five seconds and let it out through their mouth as before. Relaxing music may help them slow down and get into the right frame of mind.
For muscle relaxation pretend to be a ragdoll and make your bodies go all limp, or “shake like a dog”, pretending to be a dog and shake as a wet dog would to get dry, shaking all over.