Weighted blankets are fantastic to settle down the "wiggles" anytime of the day, but especially at night. A heavy blanket can be very calming to a person affected by Autism.
It is always best to consult with your occupational therapist when choosing a weight, but a good rule of thumb is about 10% of your weight. You can adjust up or down depending on your child's muscle tone or strength.
Weighted blanket - Blankets with Weights - Heavy Blanket