Relaxation exercises
After a couple of weeks daily practice under your supervision, your child will have developed enough skill to use these excercises to get rid of unwanted body tension (I still have to do this with ds, so it might be something that your ds will always need help with)
Set aside 20 minutes a day to do these relaxation exercises with your child.
Try to arrange to be on good terms with your child when you do these exercises so your child looks forward to them.
Do them at the same time and in the same place every day.
Before you begin, remove all distractions (by turning off bright lights, the radio etc) and ask your child to loosen any tight clothes (like belts, ties, shoes)
Ask your child to lie on a bed or recline in a comfortable chair with the eyes lightly closed.
Before and after each exercises ask your child to breathe in deeply and exhalf slowly three times while saying the word 'relax' to themself.
At the end of each exercise praise your child by saying 'well done;' or 'you did that exercise well' or some other form of praise.
Repeat each exercise twice.
Throughout the exercises speak in a calm, relaxed, quiet voice.
HANDS
Close your hands into fists. Then allow them to open slowly. Notice the change from tension to relaxation in your hands and allow this change to continue further and further still, so the muscles of your hands become more and more relaxed.
ARMS
Bend your arms at the elbow and touch your shoulders with your hands. Then allow them to return to the resting position. Notice the change from tension to relaxation in your hands and allow this change to continue further and further still, so the muscles of your arms become more and more relaxed.
SHOULDERS
Hunch your shoulders up to your ears. Then allow them to return to the resting position. same as above about notice the change etc
LEGS
Point your toes downwards. Then allow then to return to the resting position. Then same as above.
Point your toes upwards. same as above.
STOMACH
Take a deep breath and hold it for 3 seconds, tensing the muscles in your stomach as you do so. Then breathe out slowly. Same as above.
FACE
Clench your teeth tightly together. Then relax. Same as above.
Wrinkle your nose up, then relax. Same as above.
Shut your eyes tightly, then relax. Same as above.
ALL OVER
Now that youve done all your muscle exercises check that all areas of your body are as relaxed as can be. Think of your hands and allow them to relax a little more. Think of your arms, shoulders etc, etc, etc.
BREATHING
Breathe in....one....two.....three and out slowly one, two three, four, five, six and again. Repeat 3 times.
VISUALISING
Imagine you are lying on a beautiful sandy beach and you feel the sun warm your body.
Make a picture in your mind of the golden sand and the warm sun.
As the sun warms your body you feel more and more relaxed. Repeat this 3 times.
The sky is clear, clear blue, above you can see a small white cloud drifting away into the distance.
As the cloud drifts away you feel more and more relaxed. Repeat this 3 times.
As the sun warms your warms your body, you feel more and more relaxed. As the clouds drift away, you etc, etc, etc.
Wait 30 seconds, open your eyes, ready to face the rest of the day, relaxed and calm.
Blimey i almost fell asleep typing that 
Have to say ds found it very difficult to keep still for 20 minutes to start with, so we did a quicker version or his brain just sending a message and imagining the message travelling down his arms, through his stomach, down his legs, until it reached his feet. Then the same thing to other body parts. You could adjust to what you feel your ds could cope with or tolerate the best.
We also changed the visualising, ds wanted to imagine me and him riding unicorns through the sky.(going to sleep with happy thoughts really helped with nightmares)
We also had a months worth of Melatonin to induce sleep and reset his body clock.