The question is....Do I need weight or pressure for my child?
The answer is...it depends.
We all respond differently to touch and pressure. Some of us like strong hugs, others don't. Some of us sleep weighted down with covers, others prefer nothing at all. Very often children with autism, sensory integration disorder, ADHD and other neurological challenges respond well to either weight or pressure. The theory is that, for reasons beyond the scope of this discussion, their nervous system does not perceive and understand proprioception (perception mediated by nerve endings concerning movement and position). It is as if the nervous system does not understand what is happening in the rest of the body. It continually sends messages saying, "hey what's going on?" and in response the body moves saying, "we're OK."
What we often see are children who are constantly on the move and even so not understanding their movement. When additional weight or pressure is applied, the brain gets a clearer understanding of what is going on and the child is thus able to concentrate on more important tasks such as writing, reading, eating, etc. Whereas some children need the pressure applied for long periods of time (a pressure vest) others may do well with interval pressure (a weighted vest, being squashed inside a mat...with supervision of course). It depends on the child and is often a process of trial and error
Please remember that weight or pressure alone can not be considered a "fix-all". Used in combination with behavioral modification and other therapies, a weighted or pressure product can be highly beneficial.